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GOVERNORS 



AND 



GOVERNING MECHANISM. 



BY 

H. R. HALL, 

Mechanical Engineer. 



PRICE TWO SHILLINGS AND SIXPENCE NET. 

■w i d » ■* a 3 -a , ^ , 

. ... i ..... . 



1903. 

THE TECHNICAL PUBLISHING CO., LIMITED, 

287, Deansgate, Manchester. 

JOHN HEYWOOD, 

29 <fc 30, Shoe Lane, London ; and Ridgefield, Manchester. 
And all Booksellers. 



PKEFACE. 



The first few chapters of this book give a general description of the 
principles underlying the action of the steam engine governor. 

In discussing these, the ideal of "regularity " is substituted for that 
of isochronism. Also, difference of speed, and consequently difference 
of centrifugal force, is taken to be that on which the power of a 
governor depends. 

Chapters IX. to XIV. deal with valve gears, and give a method of 
designing the governor in connection therewith. 

The remaining chapters deal with governors in which the principles 
involved differ somewhat from those which underlie the action of the 
ordinary governor. 

Two appendices have been added, one dealing further with governor 
power, and the other, suggested by the Editor of The Practical 
Engineer, giving numerous examples of governors and governing 
mechanism by well-known makers. 

The writer wishes to express his best thanks to the Editor of The 

Practical Engineer for obtaining, and the various firms and gentlemen 

connected therewith whose governors and gear are described in the 

book for supplying, blocks and drawings for illustration, descriptive 

matter, and other information. 

H. R. HALL. 

Birmingham, 

July, 1903. 



ERRATUM. 



Page 3, bottom line, for "centrifugal force," read "energy from 
which centrifugal force is derived." 



CONTENTS. 



PAGK 

Introduction 1 

CHAPTER I. 
The Conical Pendulum 2 

CHAPTER II. 
Centrifugal Force 3 

CHAPTER III. 

Watt's Governor — The Principle of Supply and Demand — Fluctuations 8 

CHAPTER IV. 

The Isochronous Governor— A One-speed, any-pnsition Governor — Admits of 
no Fluctuations, therefore cannot act on the Principle of Supply and 
Demand . 10 

CHAPTER V. 
Qualifications that a Governor should Possess 15 

CHAPTER VI. 

Qualifications that a Governor should Possess— Power and Sensitiveness .... 15 

CHAPTER VII. 
Qualifications that a Governor should Possess — Regularity 24 

CHAPTER VIII. 

Qualifications that a Governor should Possess — Steadiness and Lightness.. . . 29 

CHAPTER IX. 
Governor Gear 32 

CHAPTER X. 
Throttle Valve Gear 32 

CHAPTER XL 
" Automatic " Slide Valve Gear 34 



VI. CONTENTS. 

CHAPTER XII. page 
' ' Automatic " Trip Valve Gear 45 

CHAPTER XIII. 

Position of Governor Ball and Gear for Different Points of Cut-off -Slide 
Valve Gear— Trip Gear 50 

CHAPTER XIV. 

Positions of Governor Ball for Different Speeds within the Total Variation . . 54 

CHAPTER XV. 
The Crank Shaft Governor , 5? 

CHAPTER XVI. 
The Inertia Governor 5S 

CHAPTER XVII. 
Gas Engine Governors 62 

CHAPTER XVIII. 
Relay Governors 66 

APPENDIX I. 
Governor Power 72 

APPENDIX II. 

Examples of Governors and Governing Mechanism by various makers 76> 



LIST OF ILLUSTRATIONS, <fcc. 



FIG. PAGE 

1. Diagram of Conical Pendulum 6 

1a. Diagram of Swinging Pendulum 6 

2. Watt's Governor and Throttle Valve , 9 

3. Cross-armed Governor 11 

4. Cross-armed Governor, Diagram of 12 

5. Cosine or Hypotenuse Governor 13 

6. Porter Governor 18 

7. Pickering Governor , 19 

8. Hartnell Governor 20 

9. Combination Loaded Governor 21 

10. Willans Governor 22 

11. Speed and Load Curves (Single-cylinder Engine) 25 

12. Speed and Load Curves (Double-cylinder Engine) 2(5 

13. Table of Powers of Pickering Governors 33 

14. Crank Shaft Governor 35 

15. Governor and Valve Gear — One Slide Valve — Two Eccentrics 36 

16. Allen Link Gear 36 

16a. Allen Link Gear — Diagram showing Action of Link 37 

17. Governor and Valve Gear — Hartnell's 38 

18. Governor and Valve Gear — Hartnell's Modified 39 

19. Diagram of Modified Hartnell Gear 39 

20. Governor and Meyer's Gear 40 

21. Governor and Ryder's Gear 41 

22. Governor and Trapezium Gear 43 

23. Table of Automatic Expansion Gears (Slide Valve) 44 

24. Table of Powers of Hartnell Type Governors 45 

25. Governor and Trip Gear (Corliss) 47 

26. Governor and Trip Gear (Drop Valve) 47 

26A.Diagram for Setting Eccentrics on Side Shaft— Drop Valve Engines 48 

27. Governor and Single Eccentric Trip Gear (Corliss) 49 

28. Governor and Single Eccentric Trip Gear (Drop Valve) 49 

29. Governor and Valve Diagram— Allen Link — One Slide Valve 50 

29a. Governor and Valve Diagram— Hartnell Gear— Two Slide Valves 51 

30. Governor and Valve Diagram — Trapezium Gear — Two Slide Valves 52 

31. Governor and Valve Diagram — Trip Gear 53 

32. Governor and Speed Diagram 55 

33. Governor and Speed Diagram 56 

34. Speed and Load Curve — Hartnell Governor. 56 

35. Shaft Governor and Dodd's Wedge Motion „ „ 57 



VliL LIST OF ILLUSTRATIONS. 

FIG. PAGE 

30. Kite's Shaft Governor 61 

37. Gas Engine Governor— Crossley's Centrifugal 03 

3S. Diagram showing Periodical Fluctuation of Speed— Gas Engine Governor 64 

39. Gas Engine Governor— Crossley's Inertia . , 65 

40. Relay Inertia Governor 68 

41. Relay Inertia Governor — Diagram of Levers 69 

42. Relay Inertia Governor — Diagram of Levers 69 

43. Relay Inertia Governor — Another Arrangement 70 

44. Relay Centrifugal Governor, Knowles' 71 

45. Hartnell's Patent Automatic Expansion Gear 77 

46. Galloway's Patent Parabolic Governor and Automatic Gear Plate 

47. Galloway's Parabolic Governor 78 

48. Tangye-Johnson Automatic Gear 79 

49. Proell Automatic Expansion Apparatus 80 

50. Engine fitted with above and Corliss Distributing Valve 81 

51. Proell Governor 82 

52. Prodi's Patent Two-valve Releasing Gear 84 

53. Messrs. Marshall's Engine fitted with above 86 

54. Richardson-Rowland Patent Drop Valve Gear 87 

55. Richardson-Rowland Patent Drop Valve Gear 89 

56. Engine fitted with Frikart Corliss Valve Gear 90 

57. Hick-Hargreaves Patent Steam Dash-pot for ClosiDg Corliss Admission 

Valves 92 

58. Hick-Hargreaves Patent Steam Dash-pot for Closing Corliss Admission 

Valves Plate 

59. Fraser and Chalmers' Reversing Trip Gear 95 

60. Fraser and Chalmers' Reversing Trip Gear 95 

61. Fraser and Chalmers' Whitmore Patent Controller for Reversing Engines 

with Trip Gear 96 

62. Fraser and Chalmers' Whitmore Patent Controller for Reversing Engines 

with Trip Gear 96 

63. Corliss Winding Engine fitted as above Plate 

64. Fraser and Chalmers' Combined Air and Speed Governors 100 

Diagram I. : Figs. 1, 2, and 3. Sections of above Plate 

65. Tangye's Shaft Governor 106 

06. Robinson's Patent Shaft Governor Plate 

67. Robinson's Patent Shaft Governor for Throttle Valve Plate 

68. Butler's Flywheel Governor for Gas and Oil Engines 108 

69. Throttle Regulator for above 109 

70. Crossley's Automatic Cut-off Gear for Gas Engines Plate 

71. Indicator Diagrams from Engine fitted with above Ill 

72. Dunlop's Patent Marine Engine Governor Plate 

73. Longitudinal Section of Vessel with above Plate 

74. Cross-section of Vessel with above Plate 

75. Aspinall's Patent Marine Engine Governor 114 

76. Aspinall's Patent Marine Engine Governor in Position on Air Pump Lever 115 

77. General arrangement of above on engine Plate 



GOVERNORS 
GOVERNING MECHANISM. 



Introduction. 



No one ever thinks of writing on the subject of Governors 
without commencing with a description of the conical or 
revolving pendulum. 

1. Therefore it will be necessary to commence this book 
with the time-honoured reference to the conical pendulum, 
and the use made of it by James Watt in setting it to operate 
the throttle valve of a steam engine, showing how he thus 
brought into mechanical science a very beautiful application 
of the law of supply and demand. 

2. It is proposed to describe, according to custom, the 
astatic or isochronous " governor/' and to attempt to show, 
contrary to custom, that this instrument is not a governor, 
because it does not possess one of the essential qualities of a 
governor ; that, in fact, to say that a governor should be 
isochronous, or nearly so, is misleading. 

3. It will be endeavoured to show what are the essential 
qualities that a governor should possess, and how these 
qualities affect the determination of the size and power of a 
governor for the ivork it has to do. In doing which it will 
be necessary to consider some of the various forms of valve 
gear with which the governor is connected, and which, 
together with the governor, form the governing mechanism. 

4. It is intended to show how these qualities affect certain 
well known special forms of governor, such as the shaft 
governor, the inertia governor, gas engine governors, and 
relay governors. 

2gm 



GOVERNORS AND GOVERNING MECHANISM. 



CHAPTER I. 

The Conical Pendulum. 

If two equal-length pendulums be set swinging through 
equal arcs at right angles to each other, in such a way that 
one comes to rest when the other is in the middle of its 
swing, and these two motions be combined, the result will be 
what is known as uniform circular motion. 

Because : " Uniform circular motion is compounded of two 
simple harmonic motions of equal period and amplitude, 
taking place at right angles to each other and differing in 
phase by one quarter of the whole period." (Goodeve, 
" Elements of Mechanism.") And the motion of a pendulum 
is a simple harmonic motion. If, instead of two pendulums 
one and the same pendulum be set swinging sideways as well 
as forwards in the manner indicated, that is, if it is revolved 
it will, nevertheless, perform its vibration approximately in 
the same time as if left to swing forwards only. 

The revolving or conical pendulum will describe a half- 
circle approximately in the same time that the swinging 
pendulum will make one vibration. (See note at end of 
•Chapter II.) 

From this fact and the law which gives the time that a 
pendulum of given length will take to make one vibration, 
the formula for finding the height of the cone or the point 
of suspension above the plane in which the balls revolve, of 
the conical pendulum revolving at a given speed may be 
derived. 

This height is inversely proportional to the square of the 
speed, and if it is remembered that the height for sixty 
revolutions per minute is 9*78 in., or roughly, 9| in. (which 
is the length of a pendulum to vibrate twice per second,) it 
is only a matter of simple proportion to find the height for 
.any other speed. 



CENTRIFUGAL FORCE. 3 

CHAPTER II. 

Centrifugal Force. 

To demonstrate this principle of the conical pendulum it 
is necessary to first consider the force which compels a body 
to move in a circle. Newton established " that whenever a 
body describes a circle with uniform velocity it must be sub- 
ject to a constant force tending towards the centre of the 
circle." 

The force which resists this is called centrifugal force. 
Centrifugal force is due to inertia, and the tendency of a 
moving body to continue its motion in a straight line and 
with unvarying velocity. 

The attempt to change the motion of a mass is met by a 
resistance on the part of the mass which is exactly propor- 
tionate in amount to the rate of change, and is felt in a 
direction exactly opposite to that of the change of motion, 
that is, in this case, at right angles to the circumference of 
the circle. This force must not be confused with that 
derived from the energy possessed by a body moving with 
uniform velocity or with the energy stored up in a flywheel 
or other revolving body. That energy is the weight of the 
moving body multiplied by a certain height, i.e., the height 
to which a body must be raised so that by falling from that 
height in vacuo it may acquire the velocity of the moving 
body. 

The force which this energetic body may display depends 
on the rate at which it is stopped. Centrifugal force is due 
to a different cause. This is constantly acting and resisting 
the continual effort necessary to change the direction of 
motion of the mass from that of the straight line into that 
of the circle. It is a constant uniform bursting pressure, 
and acts in exactly the same way as pressure admitted to 
the inside of a cylinder. 

Then the weight multiplied by the height due to the rate 
at which a revolving body is constantly being pulled towards 
the centre of the circle in which it revolves is the centrifugal 
force. 



4 GOVERNORS AND GOVERNING MECHANISM. 

To find this in terms of the radius will necessitate a refer- 
ence to proposition 36 of the third book of " Euclid," and 
sundry other matters : " If a line be drawn at a tangent to 
a circle, and from a point in this line outside the circle, 
another line be drawn through the centre of the 
circle, the rectangle contained by the whole line passing 
through the centre of the circle and the part of it outside 
the circle will be equal to the square on the part of the line 
drawn at a tangent to the circle." — "Euclid," prop. 36, 
book 3. 

The distance that a body would be moved through by the 
force which compels it to move in a circle, in the time that 
it took to move through the part of the line drawn at a 
tangent to the circle, would be represented by that part of 
the line passing through the circle which lies outside it. 

Let the distance = x, and the other distance, viz., that 
along the tangent = y, then 

x ( 2 r -f x) = y 2 , or 2 r x + x 2 — y 2 . 

Let the distance y be very small ; y may be taken as 
equal to the arc of the circle, and x 2 may be neglected, 
therefore 

2 r x = y 2 . 

But the force which compels a body to move with uniform 
velocity is 

w x velocity generated in one sec. m 
9 

or, putting / for the velocity generated in one second in the 
body of weight w by the action of the force F, 

F = Zf; 

9 

And the distance moved through by a body in a given time is 
time* 2 x vel. generated in one sec. 



2 
therefore x - h ft. 2 . 



CENTRIFUGAL FORCE. 

Also, the motion in the circle is uniform, therefore 

y = t x velocity. 
Therefore 2r x i ft.' 2 = r v 2 



and fr = v~ — that is,/ = 



v 



v 



tf) v 



Therefore F = _ -, or wrN 2 '00034, 

when iv = weight, 

v = velocity feet per second, 

g — velocity feet per second acquired by a body in 

falling from rest in one second, viz., 32*2, 
r = radius of circle in feet, 
X = revolutions per minute. 

So much for centrifugal force, which has been described 
at some length, because it not only enters into this demon- 
stration of the principle of the conical pendulum, but is the 
force on which almost all governors depend for their action, 
to say nothing of its importance in connection with other 
mechanical matters. 

It is now possible to proceed with the demonstration of 
the principle of the conical pendulum. Let D, fig. 1, 
represent the ball suspended at an angle by the a v m C. 
D, when the governor is revolved, is acted on and held 
in equilibrium by three forces, two of which are known, 
viz., the weight acting downwards and the centrifugal force 
acting outwards ; the third force is the pull of the arm C, 
and is the resultant of the other two. 

By the principle of the parallelogram of forces, the radius r, 
or the distance of the ball from the centre of the point of 
suspension, bears the same proportion to the centrifugal 
force that the weight bears to the height h, or the point of 
suspension above the plane in which the ball revolves — 
that is, 

w v 2 7 
: w : : r : li\ 



6 



GOVERNORS AND GOVERNING MECHANISM. 



i.e., multiplying together extremes and means, and elimina- 
ting the common factor w, 



v 1 h 
gr 



r, or v' h = g r~ ; 



this, again, is the same thing as 



!h 



J' 




■C.F 



Fig. 1. 




Fig. la. 



and, as the motion is uniform, the time of a revolution 
multiplied by the velocity, or t v is equal to the diameter of 
the circle, or 2 r x 3*1416 — that is to say 



t = 



3-1416 6-2832 



- 6-2832 



IT 



J 



9 



Thus it is seen that the time of a revolution varies 
directly as the square root of the height of the cone, which 
is the same thing as saying that the height is inversely 
proportional to the square of the speed, as before stated. 



CENTRIFUGAL FORCE. 



Note on the time of swing of a pendulum communicated by Mr. W. 
Hewson, A.R.C.S. :— 

The time of swing of a governor ball is 



^9 



strictly— i.e., a ball at a point with weightless arms, etc. But the 
time of swing of a pendulum is not exactly 

T = 2 7T Jl 

V 9 

not even for a simple ball suspended by a weightless string from a 
frictionless point of support, etc. The time varies with the angle, and 
is greater the greater the angle. The reasons being— 

(a) That in the governor, the force on the ball holding it in towards 
the centre of the circle in which it swings is proportional to r, fig. 1,. 
its distance from that centre, and therefore produces harmonic motion. 

The balls moving in a circle, the points on a diameter of the circle 
which are projections of the balls on that diameter, move backwards 
and forwards as in harmonic motion. 

(b) In a pendulum, on the other hand, the force is not proportional 
to the distance along the path to the position of equilibrium. See 
fig. la. 



In harmonic motion T = 2 w j Stance 

v acceleration 



But in pendulum T = 2* / length of pendulum x fl (or are) 

V g sin d 

For acceleration = f ^ e = g sin 6 along tangent, 
mass 

Now if arc {I 6) were equal to A B (I sin 6) T would be equal to 

^9 
but it is not. 

The nearer the arc approaches to A B, or the smaller the angle d, the 
nearer is 

T = 2 7T A . 

So the formula usually given for a simple pendulum is only true for 
indefinitely small arcs, and the true formula for a simple pendulum is 
not the same as for a governor except approximately. 



8 GOVERNORS AND GOVERNING MECHANISM. 

CHAPTER III. 

Watt's Governor. 

The conical pendulum attached to a throttle valve is the 
oldest and most venerable form of centrifugal governor. 
As used by Watt, it consisted of two heavy balls carried at 
the ends of rods suspended from a central spindle, which 
was driven from the engine shaft by cord or belt. The 
arms were prolonged at the top, and connected by links 
to a collar which actuated a lever connected with a 
butterfly valve in the steam pipe, fig. 2. 

When the balls rose, due to an increase of speed, the 
valve closed, diminishing the supply of steam so as to bring 
down the speed to its proper level. When the balls fell, 
owing to a decrease of speed, the valve opened, increasing 
the supply of steam so as to bring the speed up again. 
The principle of this action is that of supply and demand. 

It is a curious fact that, while political economists 
recognise that for the proper action of the law of supply and 
demand there must be fluctuations, it has not generally 
been recognised by mechanicians in this matter of the steam 
engine governor. 

The aim of the mechanical economist, as it is that of the 
political economist, should be not to do away with these 
fluctuations altogether (for then he does away with the 
principle of self-regulation), but to diminish them as much 
as possible, still leaving them large enough to have sufficient 
regulating power. 

This, then, was Watt's governor, operating on the 
principle of supply and demand. 

The principle on which the Watt governor operated is the 
same as that on which all simple governors act. By simple 
governors is meant those which render an engine in itself 
self-regulating. Auxiliary or supplementary governors, 
involving the principle of interference by some outside 
agency are generally too complicated to stand much chance 
of competing successfully with governors operating on this 
simple principle. 



WATT S GOVERNOR. 




Fig. 2. 



10 GOVERNORS AND GOVERNING MECHANISM. 



CHAPTER IV. 

The Isochronous "Governor." 

It will now be necessary to describe the Astatic or 
Isochronous " Governor/' 

A governor is said to be static when it will maintain the 
balls in a definite position for any given speed, and when it 
is capable of resisting external forces tending to alter their 
position. The instrument is astatic when the balls assume 
indifferently any position at the same speed, and offer no 
resistance to external forces tending to alter their position. 
This is what is called the " Isochronous Governor," from 
the Greek " isos "— equal, and "chronos" — time. The 
isochronous governor may be called a one-speed, ewy-position 
governor, in contradistinction to the static, or one-speed op- 
position governor. Considering the uselessness of such an 
instrument for the purpose of a governor, it would be 
remarkable that so much time and thought should have 
been devoted by mechanicians to its construction, if it were 
not that it is a very beautiful piece of mechanism. 

The simplest form of this instrument is the so-called 
parabolic governor. The parabolic governor was made in 
Germany (strictly speaking, Vienna), and brought over to 
this country in 1851. It is a modification of the conical 
pendulum. If, instead of allowing the balls of the 
pendulum governor to describe, as they rise, an arc of a 
circle, they are constrained to move in a parabolic curve 
such a governor would pass through its entire range at the 
same number of revolutions per minute. For it is a property 
of the parabolic curve that the height of the cone is always 
constant ; and it has been shown that there is only one 
speed for one height of cone. If, therefore, in the governor 
opening out the height of the cone does not vary, the speed 
does not vary. 

The commonest method of constructing an approximately 
parabolic governor is to cross the arms in such a way that 
their point of intersection rises by the same amount as the 



THE ISOCHRONOUS M GOVERNOR. 



11 



plane of revolution of the balls. This is what is known as 
the X-armed type. (Fig. 3.) 

A curious property of the X-armed governor is that it can 
be so constructed that the balls, instead of rising when the 
speed increases, will actually fall and describe a smaller 




LTD 



LjJ 



Fig. 3. 



circle when running at a higher, than when running at a 
lower speed. It is merely necessary to arrange the points of 
suspension so that the arms cross in such a manner that the 
height of the cone diminishes as the balls descend; i.e., to 



12 



GOVERNORS AND GOVERNING MECHANISM. 



make the distance between the points of suspension 
greater than the distance between the centres of the balls, 
as in fig. 4, and the rest follows from what has been seen as 
to the relationship between the height of the cone and the 
speed. 

Another very beautiful example of this type, viz., the 
parabolic type, is the cosine governor, so called because the 




Fig. 4. 



actual length of the arm must be multiplied by the cosine 
of the angle made by the hypotenuse to give the virtual 
arm. (Fig. 5.) The arms of this governor are two bell 
cranks, the ends of the short arms overlapping each other 
in such a way that lines drawn from them to the centre of 
balls will cross at a point below the plane of suspension. It 



THE ISOCHRONOUS "GOVERNOR. 



13 



is possible to arrange the arms so that the point of intersec- 
tion of these imaginary lines will rise by the same amount 
as the plane of revolution of the balls. This imaginary line 
is called the hypotenuse, hence this is sometimes called the 
hypotenuse governor. 




Fig. 5. 



It is possible to arrange this governor so that it is in 
perfect isochronism for any length of range, whereas, in the 
X-armed type, the range is limited. 

The isochronous governor, when running at its proper 
speed, offers no resistance to external forces tending to alter 



14 GOVERNORS AND GOVERNING MECHANISM. 

the position of the balls, therefore it is not capable of 
maintaining the throttle valve or the valve gear in any one 
position, but will maintain them indifferently in any position, 
so accommodating is this governor (throttle valve wide open 
or quite closed), and on the slightest provocation or change 
of speed will run at its extreme top or bottom position, 
according to whichever way the speed may be changed. To 
remedy the unsteadiness of such a governor, as it is called, 
it is usual to provide it with a dash-pot. 

The effect of the dash-pot is to prevent any immediate 
alteration in position of the balls when acted on by external 
forces, or by a change of speed ; but it does not prevent 
their ultimate alteration to the extreme top or bottom 
position, and therefore does not make the governor any more 
capable of adjusting the steam supply arrangements to the 
requirements of the engine. The governor has still no 
mind of its own, so to speak. The dash-pot simply delays 
the movement of the governor, and delays are sometimes 
dangerous, especially when an engine is running away and it 
devolves on the governor to check it. 

It was said that the principle of the action of all simple 
governors is that of supply and demand. When the greater 
demand made on the engine for power, which occasioned the 
fall of speed and, consequently, the greater opening of 
throttle valve is maintained, the fall of speed must also be 
maintained and vice-versa. Therefore it will be necessary 
for the balls of a governor operating on this principle to 
occupy a definite position and maintain the throttle valve to 
a definite opening for a given speed, and it must be capable 
of resisting external forces tending to alter this position. 
Therefore, the governor must have one speed for one 
position, another for another. The difference of speed 
between any two positions need be only very small, in fact, 
the smaller the better ; but a difference there must be. 
That is, the governor must be decidedly static. But the 
governor just described is isochronous or astatic, which is 
the opposite of what is required. 

This leads to a consideration of the first and most 
important qualification that a governor should possess, and 
that is power. It is usual to say that a good governor must 



POWER. 15 

be, first, "isochronous or nearly so." To say that a governor 
must be isochronous or nearly so, is equivalent to saying 
that it must have no power, or nearly none. It must have 
power to resist external forces tending to alter the position 
of the balls, and power to adjust the steam supply arrange- 
ments to the requirements of the engine. 



CHAPTER V. 

Qualifications that a Governor should Possess. 

The qualifications that a governor should possess, then, are : 

1st. Power, and to possess this, it must be static, or be 
a one-speed, one-position governor, and not a one-speed a/im- 
position governor. 

2nd. Sensitiveness, i.e., the difference in speed between 
the two extreme positions should be small. 

3rd. Regularity, i e., the differences in speeds between 
any two equal intermediate positions should be alike. 

4th. Steadiness, and 

5th. Lightness, which, though not an essential quality, is 
still a very desirable one. 

It wdll be endeavoured to show that the sensitiveness of a 
governor depends on the degree in which the first and third 
of these properties, viz., pow r er and regularity, are possessed 
by a governor, and not on its approximation to isochronism 
as is generally supposed. 



CHAPTER VI. 

Power. 

The power available in any ordinary centrifugal governor 
to do the work of shifting the eccentric or valve, to give a 
greater or less admission of steam, for a heavier or lighter 
load, is the mean of the difference of the centrifugal force of 



16 GOVERNORS AND GOVERNING MECHANISM. 

the balls at two different speeds of the governor or engine, 
within which it is allowed to run, multiplied by the distance 
between the two positions of balls. 

If two governors be taken for comparison, each having the 
same percentage of variation, that is, the same sensitiveness 
and the same range, then the power of the one is to that of 
the other as the difference of centrifugal force in each case. 
And these differences are, it can be proved, one to the other 
as the mean centrifugal force in each case. 

That is, if a : b : c : d, 

then a 2 - b 2 : c' 2 - d 2 ::( - - — ) ' ( — - — ] 

for by componendo and dividendo : 

a - b _ c - d. 
a + b c + c/.' 

Therefore : 

(a + 6) (a - b) __ (c + d) (c - d) 



Therefore 



(a + b)' 2 (c + </)- 



(a + by 2 



(a + b) (a - b) _ (a 4- b) 2 



(c + d) (c - d) (c + d) 2 " (g + d )~ 

2 
Therefore 



a' 2 - b' 2 

c' 2 - a 2 



(4 ") 2 



Then the power of the one governor is to that of the other 
as the centrifugal force simply, taking the mean speed in each 
case ; that is, the relative power of any two governors of the 
same sensitiveness, and with balls describing the same 
radii, can be readily compared by taking in each case the 
weight of the balls and multiplying by the square of the 
speed. 



POWER 17 

A governor with balls of twice the weight of another, 

running at the same speed, will have twice the power, but a 
governor with balls of the same weight, running at twicethe 
speed, will have four times the power. The readiest way, 
then, to increase the power of a governor, is to increase the 

speed. 

It will now be seen why the conical pendulum is not 

often used in these days of high speeds and high pressures, 

governor. Not because it is not isochronous, as is 

sometimes said, but because of the difficulty of increasing 

its power without enormously increasing the weight. Let it 

be required to run the Watt governor at 200 revolution 
minute — a not uncommon speed for a governor — the height 
of the cone would be '88 in. This is obviously impracticable. 

A further point relating to the Watt governor may be 
here mentioned. It was seen that the height of the point of 
suspension above the plane in which the balls revolve was 
inversely proportional to the squares of the speeds, and it is 
now said that the power of a governor, the weight being the 
same, is in proportion to the square of the speed : therefore 
the height of the cone in the Watt governor is inversely 
proportional to the power. 

The power of a governor depends on the centrifugal 
force, but if the ball is to be maintained in any one position 
it must be in equilibrium in this position : that is, it must 
be acted on by another force which exactly balances this. 
In the pendulum governor this was the weight of the ball 
itself. 

If it is required to increase the centrifugal force without 
Increasing the weight of the ball, then some other force must 
be introduced : that is, the governor must be loaded. All 
modern governors, of whatsoever so-called variety, are of 
this class. The load may consist of a dead weight simply, 
or a spring simply, or a combination of the two. 

In the Porter governor, fig. o, it consists of a dead 
weight simply, hung on the central spindle, the arrangement 
of the arms being similar to the Watt or X-armed variety. 
In this case the weight of the balls themselves contribute 
something towards the resistance to centrifugal force ; the 
3gm 



18 



GOVERNORS AND GOVERNING MECHANISM. 



remainder — by far the greater portion — being made up by 
the dead weight or counterpoise, as it is called. 

In the Pickering governor, rig. 7, the loading is not so 
apparent, but consists of the resistance to bending of the 
flat laminated springs which constitute the arms of this 
governor. 






/ .x. 




Porter Governor, 



Fig. 8 is a spring loaded governor of the Hartnell type, and 
fig. 9 is a governor in which the load consists of a combina- 
tion of spring and dead weight 

This governor is a modification of the bell crank lever type, 
with a rising head forming the dead weight part of the load- 



POWER. 



19 



ing, and consists of the head A carrying the bell crank levers 
and balls B ; the spindle C driven by bevel wheels and 




Fig. 7. — Pickering Governor. 



pulleys from the crank shaft the fixed stem D, on which 
the head revolves, and the spring E. 

A washer forming an oil box F, makes up the distance 
between the face of stem on which it turns, and the head 



20 



GOVERNORS AND GOVERNING MECHANISM. 



of the spindle driving the governor. This also forms a 
guide on which the bored part of the governor head slides. 

The centrifugal force of the balls B, pressing on the top 
of the spindle through the bell crank levers, lifts the head 



.. X 




Fig. 8.— Hartnell Governor. 



compressing the spring against the underside of the washer 
F. The lift of the head is given to the expansion valve 
through the levers and rod as shown in fig. 22, Chapter XL 



POWER. 



21 



Loaded governors are the only governors with which any 
one, in these days, need concern himself, and the only thing 




Fig. 9. 



\ 



/ 



to remember concerning them is that the moment of the 
load must equal the moment of centrifugal force \ that is, 



22 



GOVERNORS AND GOVERNING MECHANISM. 



CENTRE LINE OF 
CRANH SHAFT 





Fig. 10.— Willans Governor. 



SENSITIVENESS. 23 

the load multiplied by the distance through which it is 
moved must equal the centrifugal force multiplied by the 
distance through which it acts. 

In a governor arranged like Willan's, fig. 10, with balls 
attached to opposite ends of the same spring or springs, it is 
only necessary to consider the centrifugal force due to one 
ball, because the balls pull one against the other — the 
centrifugal force of one forming the reaction for the centri- 
fugal force of the other. 

The spring or springs would require to exert only half the 
force with twice the extension of a spring arranged in the 
ordinary way; that is, with the centrifugal force of both 
balls acting in the same direction, the spring supported at 
the other end against a fix^d stop. 

Since it is difficult to make a spring within the length 
available that will give sufficient extension with so small an 
increase of resistance, this governor is fitted with compen- 
sating springs F, on the throttle valve spindle, which act 
with the centrifugal force, causing the loading to increase at a 
more conveniently rapid rate. These springs being outside 
the governor also afford a means of varying the resistance, 
hence the speed of the engine while running. 

It will now be seen that the power of governors, having* 
the same percentage of variation, and the same range, may 
also be compared by comparing the loads ; that is, 
the weight of the counterpoises, or the strength of the 
springs. 

Sensitiveness. 

In addition to a governor being powerful it should be 
sensitive * that is, the difference in speed between the two 
extreme positions taken up by the balls should be small. It 
was seen that the power of a governor depended on the 
difference of centrifugal force of the balls at two different 
speeds. If it is required to do more work with a governor, 
without increasing the mean speed, it can be done by 
increasing the difference in speed between the two extreme 
positions. But this is to increase its variation, or diminish 
its sensitiveness. If, therefore, it is required to increase its 
sensitiveness, still leaving it capable of doing the same work, 



24 GOVERNORS AND GOVERNING MECHANISM. 

the power of the governor must be increased. The 
sensitiveness, then, depends upon the power. 

A governor running at 320 revolutions mean speed, and 
capable of shifting 1801b. through one inch with a 4 per 
cent variation, would require to run at 340 revolutions mean 
speed to be capable of doing the same work with a 2 per 
cent variation ; that is, the power would require to be 
increased by about 12| per cent, or Jth, to diminish the 
variation one half. 



CHAPTER VII. 

Regularity. 

The next thing a governor should possess is regularity, 
i.e., the difference in speeds between any two equal inter- 
mediate positions within the total range of variation should 
be alike. 

This is a point to which very little attention has been 
paid by engineers, with the result that very few governors 
possess this property, and are, consequently, much less 
powerful with the same sensitiveness than they might be if 
properly designed. 

The following are the actual variations in speed of a 
9 in. by 12 in. single cylinder engine, boiler pressure 851b. 
per square inch, from a table given in Proc. Inst. Mechanical 
Engineers, page 230, No. 2, 1895, and may be taken as a 
fair example of what occurs in practice : — 

Engine with Throttle Valve. 

B.H.P 20-04, 17-82, 15*54, 13'43, 11-19, 8 9, 6'61, 0. 

Difference... 2-22, 2*28, 211, 2*24, 2*20, 2-19, 6*61. 

Speed 147-2, 1477, 1481, 149'9, 151*2, 1522, 154*1, 155. 

Difference... '5, '4, 1'8, 1'3, 10, 1'9. 1*9. 

Engine with Auto or Variable Cut-off. 

B.H.P 20-5, 18-25, 16*04, 13*68, 11*34, 8*98, 6*60, 0. 

Difference. ..2*25, 2*21, 2*36, 2*34, 2*36. 2*38, 6*60. 

Speed 150-5, 151*3, 152*6, 152*8, 153*3. 153*6, 153*8, 155*1. 

Difference... "8, 1*3, *2, *5, '3, *2, 1*3. 



REGULARITY. 



25 



In the first the total variation is 5 1 per cent, and the 
least variation *4 revolutions. If this least variation were 
sufficient to govern on, between 17*82 and 15*54 B.H.P., it 
is only fair to. assume that it would have been sufficient for 
the same variation of power in any of the other positions. 
If the governor had been regular with "4 revolutions 
difference between each position, the total variation could 
have been reduced to 1 *8 per cent. In the automatic engine 
the case is even worse. Fig. 11 shows the above variations 



, /oz/p 




Fig. 11. 

in speed, plotted as curves, and fig. 12 shows the same for a 
compound double-cylinder portable engine, with cylinders 
7f in. and lljin. diameter by 12 in. stroke, boiler pressure 
135 lbs. per square inch, taken from the same source. 

It has been seen that the total power of a governor 
depends on the difference of centrifugal force when running 
at its two extreme positions, corresponding to full load and 
no load in the engine ; but in practice it is very seldom that 
the full ]oad is thus suddenly thrown off or on, and that 
the governor is called upon to exert its full power. In 
regular work the load will be more likely to vary between 
quarter or three-eighths to five-eighths or three-quarters of 
the maximum, and the governor will only be called upon to 
regulate the supply of steam to suit these variations, that is, 



2G 



GOVERNORS AND GOVERNING MECHANISM. 



h 



\ 



WAS t/J<J fAJLl 



\ 



\ 





M'S* &Jpf ±AJ1/ 


-y- - -r- 

\ 

- --U-----4- 


i i 


\ 
\ 

A _ ... . 


u ^ 


1 ~~4~ -\- 


S 


5j. J _L .0 


1 


3 T * 




FTft't 


4)1 -. 


T 


\ 

-----V 


i 

1 


\ 







KEGULARITY. 27 

to take up intermediate positions corresponding to these 
fractional loads. The power of the governor to do this work 
depends on the difference of centrifugal force between these 
intermediate positions. 

If now, the difference in speed between any two of these 
middle intermediate positions is less than it is between the 
top and bottom intermediate positions, as is nearly always 
the case in governors, then the power of the governor at 
these positions will be less than it is at the top and bottom 
positions, and less than it would be if the differences were all 
alike. That is, for the governor to have as much power at 
any intermediate position, the total variation must be 
increased by as much as the least difference of speed falls 
below the mean. If this difference amounted to one-fifth, as 
it often does, then the total variation would have to be 
three times as much. 

Thus, then, a governor should be regular, and the sensitive- 
ness depends on the power and the degree of regularity 
possessed by a governor. To construct a governor that shall 
be perfectly regular, it is merely necessary to see that the lifts 
necessary to make the equal alterations in load are arranged 
so that the governor will run with equal differences of speed 
between these positions. In other words, to arrange that 
the movements shall be proportional to the speeds. 

Although it has not been generally recognised, one of the 
chief causes of irregularity in spring-loaded governors is the 
spring itself. A well-known writer on the steam engine 
says : "In any of this class of governors (viz., spring loaded) 
it is possible to secure absolute theoretical isochronism, 
because the centrifugal force of a body revolving in a circle 
varies directly as its distance from the centre for a given 
uniform speed, and the resistance of a coiled spring also 
increases directly as it is compressed." This possibility of 
isochronism in a governor seems to have covered a multitude 
of sins, for let it be shown that a governor could be made 
isochronous, and nothing more was supposed to be required 
than to make it just not so. Let it be admitted that a 
governor must be just not isochronous, and this is where the 
trouble comes in, because then the speed must increase, and 
the centrifugal force varies not only directly as the radius, 
but also unfortunately as the square of the speed. 



28 GOVERNORS AND GOVERNING MECHANISM. 

Suppose the range of a governor to be 2 in. ; let it be 
divided into four equal parts, and let it be required to run 
with one revolution difference between each of these five 
positions, viz., at 198, 199, 200, 201, and 202 revolutions 
per minute, corresponding to a total variation of 2 per cent. 
The differences of the squares of these numbers are 397, 
399, 401, 403, or as 7, 9, 11, 13 ; that is, the spring would 
have to compress through the first | in. with an addition of, 
say, 7 lb., through the next \ in. with an addition of 9 lb., 
through the next with 11 lb, and the next 13 lb. 

But the resistance of a spring varies directly as it is 
compressed ; that is, if it takes 7 lb. to compress it through 
the first | in., it will only take 7 lb. more and not 9 lb. to 
compress it through the next I in. and so on. 

What is wanted, then, is a spring that will compress at a 
varying rate, so that the loads are not in a simple but in a 
sort of quadruple compound arithmetical progression. Thus 
the loads in the present case are 7, 16, 27, 40. An approxi- 
mation to this might be obtained by using four springs, <>ne 
offering a resistance at the rate of 7 lb. to the ^ in. com- 
pression or extension, and three each offering a resistance of 
2 lb. to the h in. compression or extension, arranged to come 
into action in the following order : — 

lb. 7 lb. 14 lb. 21 lb. 28 lb. resistances of spring 1. 

2 4 6 „ „ 2. 

2 4 „ „ „ 3. 

2 „ „ 4. 



01b. 7 lb. 1 6 lb. 27 lb. 40 lb. total resistances. 
h in. x J in. x ^ in. x i in. 

Note. — The actual resistances would, of course, be much 
greater than given here, but would vary in the same pro- 
portion. 

As the construction of a spring of this description may 
present some difficulty, it will be better to see if the same 
result cannot be arrived at by a proper arrangement of the 
valve gear ; and all that is necessary is to arrange that the 
lifts of the governor (necessarily unequal) for these equal 
differences in speed shall correspond with the several posi- 



STEADINESS. 29 

tions of the valve gear necessary for the proper supply of 
steam for equal differences of load. In other words, the 
valve gear must be made to suit the governor. It may be 
thought that such a simple and obvious condition for a 
governor would never be overlooked, but such is not the 
case. The writer knows of only two governors in which it 
is fulfilled. All that need be said farther in regard to this is 
that it is an easier matter to arrange for this condition with 
auto-gear, or variable cat-off, than with a throttle valve. 



CHAPTER VIII. 

Steadiness. 

One of the chief causes of unsteadiness in a governor is the 
unsteadiness of the engine itself. An engine may perform a 
certain number of revolutions per minute with unvarying 
regularity, and yet, at the same time, it may be turning a 
great deal faster during one part of each revolution than 
another ; that is, it may run jerky. The flywheel is to 
prevent this. The heavier the flywheel the less the jerki- 
ness, but it is impossible to do away with it altogether. 

A good single-cylinder engine may have as little as 2 per 
cent jerkiness. Any less w r ould mean an excessively heavy 
flywheel, bat a good governor feels this more or less, 
depending on its sensitiveness. 

A spring-loaded governor, loaded for a variation of 2 per 
cent, if perfectly free from friction, dash pots, &c, would be 
jerked through its wdiole range every time this variation took 
place. A governor loaded for 4 per cent w r ould be jerked 
through half its range — for 8 per cent through a quarter, 
and so on. In practice, however, the vibration would not 
amount to as much as this, as it is impossible to eliminate 
friction, resistance of valves, &c. ; but these factors are 
variable and uncertain, and cannot be relied upon to ensure 
steadiness in a governor, besides, they ought not to exist. 

Supposing, now r , part of the loading to consist of dead 
weight, then the movement of the governor, during any 



30 GOVERNORS AND GOVERNING MECHANISM. 

momentary fluctuation of speed, would depend upon the 
space that the weight could be moved through when acted 
on by the force generated by the increase of speed in the 
time. But the time is of very short duration. If the speed 
of the engine is 150 revolutions per minute, and the full 
force due to the increase of speed be token to act during 
half the time between the fluctuations, it will be acting for 
one-tenth part of a second. 

If the dead weight in the governor and connections be 
only equal to the force due to the change of speed, then the 
movement will be equal to the space described by a weight 
when acted on by gravity, viz., its own weight in falling, for 
one-tenth of a second. But if the weight be, say, five times 
this amount, then the movement will be equal to the space 
described by a weight when acted on by one-fifth gravity, or 
one-fifth its own weight for one-tenth of a second. The 
movement would amount to about y^ths of an inch, this is 
supposing the governor to be perfectly free. 

Example of steadying effect of inertia of parts : Coefficient 
of steadiness due to weight of flywheel - 50. This, at a 
speed for engine of 150 revolutions per minute, equals a 
variation of 2 per cent 300 times a minute. The increase 
of centrifugal force, due to 2 per cent increase in speed 
with balls at the same radius (in the governor taken for this 
example, see fig. 9) was 5*624 lb., and this equalled a lifting 
force of 11 "24 lb., acting five times a second for, say, one- 
tenth of a second. 

The dead weight in the governor equals, say, 50 lb., and 
the space described by a weight of 50 lb. in one-tenth of a 
second, when acted on by a force of 11 '24 lb., 

= l x i 1 ' 24 ! 9 * = '0359 ft. = 7 in. 
2 50 i lb 

Note. — In this example the weight forms part of the 
loading of the governor, but the result as regards the time 
taken to move the mass is the same, whether the dead 
weight acts with or against the loading of the governor, or 
whether it is balanced in itself, as it might be if in a 
horizontal position forming part of the valve gear. It is 
better, however, to constitute this dead weight part of the 



LIGHTNESS. 31 

loading of the governor, as it then serves the additional 
purpose of diminishing the strength of spring required. 

Thus the chief cause of unsteadiness in a governor is the 
unsteadiness of the engine itself, and to obviate this, part of 
the loading should consist of dead weight. The shaft 
governor is deficient in this respect. The shaft governor is 
a pure spring governor. Owing to its peculiar arrangement 
on the shafc of the engine it is difficult to load it otherwise. 
To obviate this deficiency the shaft governor is often 
constructed with a dash pot. But dead weight may be 
introduced forming, in this case, part of the eccentric or 
valve gear. 

Lightness. 

It has been seen that a deficiency of dead weight in the 
loading of a governor means a deficiency in steadiness ; but, 
on the other hand, lightness is a thing to be desired in a 
governor. According to a recently issued spring governor 
maker's circular, a Porter governor, which is purely a dead- 
weight governor, would weigh seven and a half times as much 
as a pure spring governor of the same power. But this 
governor would be extremely steady. 

It seems, then, that a sort of compromise should be made 
between extreme lightness and extreme steadiness in 
governors, so that a governor should be light, and yet have 
sufficient dead weight to prevent its being unduly affected 
by the jerkiness of the engine ; in fact, a certain amount of 
unsteadiness may not be altogether a disadvantage, as it 
keeps the joints free so that the governor is ready to 
respond immediately any permanent alteration of speed 
takes place. What exactly this amount should be is best 
found from practice. 



32 GOVERNORS AND GOVERNING MECHANISM. 



CHAPTER IX. 

Governor Gear. 

In order that a governor may perform the operation of 
regulating the supply of steam to an engine, it must be con- 
nected with some form or other of valve gear. Moreover, it 
must be adapted to, and designed in connection with, that 
gear. 

Generally speaking, it may be said that a governor 
regulates the supply of steam to an engine in either of two 
ways, viz. : — (1) By operating a throttle or reducing valve, 
thus reducing the pressure of steam in the steam chest 
before it is admitted to the piston. (2) By varying the 
cut-off, thus admitting steam to the piston at full pressure, 
but in varying amounts. In the first case the governor is 
known as the throttle valve governor ; in the second case it 
would be one or other of the various classes of " Automatic " 
governors. 

Automatic governors may again be subdivided into two 
classes, depending on the class of steam-distributing gear 
to which they are attached, viz. : (a) Those used in connec- 
tion with some form of slide-valve gear ; and (6) those used 
in connection with trip gears. 



CHAPTER X, 

Throttle Valve Gear. 

The action of the throttle valve is to reduce the pressure 
of steam in the steam chest according to the load on the 
engine, by partly closing the steam inlet, the cut-off 
remaining the same. 

With a constant cut-off, say five-eights of the stroke, 
and loads varying as 100, 75, 50, and 25, the mean pressure 
in the steam chest would require to he reduced by the 



THROTTLE VALVE GEAR. 



33 



throttle valve in practically the same ratio as the loads, to 
give correspondingly mean effective pressures on the piston. 
The terminal pressures, however, at this cut-off, with these 
initial pressures, would be less than with cut-off gear, as the 
steam pressure at the point of cut-off would fall considerably 
below the mean initial pressure, depending on the size of the 
steam chest. With a small steam chest the terminal 
pressures, and consequently the steam consumption for the 
same mean effective pressures, would be less than with a 



Diam. 
of 

steam 


£ CD 

Q > 

1-1 o - 


Revolutions 
minute. 


per 


d 

l-H o 

> 


Diameter 

of 
path of 
balls. 


Lifting 

power 

of 

governor. 


pipe, 


Min. 


Mean. 


Max. 


Ft-lbs. 


Inches. 


Inches. 








Per 

cent. 


Inches. 




11 


1*3 


438-75 


450 


461-25 


5 


21* to 4ft 


•529 


n 


2§ 


409-5 


420 


430 5 


5 


3| to 5| 


•98 


if 


n 


409-5 


420 


430-5 


5 


3| to i-i 


•98 


2 


2| 


409-5 


420 


430-5 


5 


3| to 5| 


•98 


n- 


2| 


370-5 


380 


389-5 


5 


4| to 7| 


2'47 


3 


2| 


312 


320 


32S 


5 


4| to 7| 


3-25 


H 


2| 


312 


320 


32S 


5 


4| to 7| 


3-25 


4 


31 


312 


320 


32S 


5 


5| to 8| 


5*45 



Fig. 13. 

Table of powers of some "Pickering" type of governors with from 3 to 5 per 
cent variation, as made by Messrs. Tangye. 

larger steam chest. In arranging, therefore, an engine for a 
throttle valve governor, the space between the piston and 
throttle valve should be kept as small as possible. 

Supposing now the rate of flow of steam to be the same 
at all positions of the throttle valve, then the openings 
necessary for it to make, in order to maintain the above 
reduced pressures in the steam chest, would exactly cor- 
respond with the loads, viz. : at half-load the throttle valve 
would be half open, and so on. But the flow of steam is not 
the same at all positions of the throttle valve ; it becomes 

4gm 



34 GOVERNORS AND GOVERNING MECHANISM. 

faster as the pressure in the steam chest is diminished, or, 
in other words, as the throttle valve closes. Therefore it is 
necessary either to make the throttle valve governor with 
movements smaller in its higher positions (throttle valve 
nearly closed) for the same alterations of speed, and larger 
in its lower positions (throttle valve nearly full open) ; or to 
so design the throttle valve that it will give a less opening 
for the same movement when nearly closed, than when 
nearly full open. 

The power required to operate a throttle valve is much 
less than that required to operate some other kinds of valve 
gear. The valve itself is usually an equilibrium valve, and 
the work to be done consists mainly in overcoming the 
friction of the spindle and stuffing box, pins, &c. 

The table, fig. 13, gives the power of Pickering governors 
for different sizes of throttle valve, with percentage of 
variation. 



CHAPTER XL 
" Automatic " Slide Valve Gear. 

A varying cut-off may be obtained : 

1. By a single slide valve having variable travel and 
angular advance of eccentric but constant lap. 

The varying travel and advance may be given : 

(a) By a single eccentric shifting on the shaft and operated 
by a shaft governor. (Example, Fig. 14.) 

(b) By two eccentrics fixed on the shaft but giving the 
variable travel and equivalent angular advance by means of 
a link and die, as in an ordinary link motion reversing gear. 
(Example, fig. 15.) 

(c) By a form of radial gear as Joy's valve gear, the Allen 
link, &c. (Examples, fig. 16 and 16a.) 

A varying cut-off may be obtained : 

2. By two slide valves having variable relative travel but 
constant negative lap on expansion valve and constant 
angular advance of eccentrics, the variable relative travel 



"automatic" slide valve gear. 



35 






CRANK 



Fig. 14. 



36 



GOVERNORS AND GOVERNING MECHANISM. 



f*#fi -****&? rfcj^f" r>-mf -3*wj- 




'AUTOMATIC SLIDE VALVE GEAR. 



37 



being obtained by having two eccentrics fixed on the shaft, 
and giving a variable travel to the expansion valve by 
means of a link and die. (Example, fig. 17.) 

3. By two slide valves having variable relative travel, 
variable angnlar advance of expansion eccentric, bnt constant 
negative lap of valve, the variation being obtained by having 
two eccentrics fixed on the shaft, and giving a variable 
travel and angular advance to the expansion valve by 
means of a compound link and die. (Example, fig. 18.) 




/S eOc//V^L€-rvr~ TO T//lr CF~ 
two SCC$ /V T///S POs/r/crS. 

Fig. 16a. 

Figure 19 is the valve diagram for this gear. 

4. By two slide valves having variable lap to expansion 
valve, but constant relative travel and angular advance of 
eccentrics. The variable lap being obtained : 

(a) By making the expansion valve in two parts, and 
separating them or closing them up by a right and left-hand 
screw r on the valve spindle as in Meyer's gear, or by other 
means. (Example, fig. 20.) 

(b) By making the back face of the main valve circular, 
with right and left-handed helical ports, and having a 
circular expansion valve w T ith edges at the same angle, and 
increasing or diminishing the effective width of the 
expansion valve by turning it as in the Kyder gear. 
(Example, fig. 21.) 



38 



GOVERNORS AND GOVERNING MECHANISM. 



«4* 




AUTOMATIC SLIDE VALVE GEAR. 



39 



(c) By making the ports in the back of the main valve 
oblique to right and left, but the face flat, and the expansion 




la:* *^iHr /foo 



Fig. 18. 



valve with edges at the same angle, and increasing] or 
diminishing the effective width of the expansion valve by 





>v \° 






~^\yyftf~ 






^^v^2sl\V" 






-^^^Sz^j&W^ 




fxpfsrec? 


4, /^r^S\ 


\ \ CPANti. 










\. fH* 





Fig. 19. 



Let distances A. A. A. = half travel of expansion valve, according to position of 
die in link when direct coupled to eccentric rod. 

Join A. A. A. to B. 

Angles of advance of expansion valve will be lines drawn through A.A.A.B., 
cutting them at D.D.D. into two parts proportional to the lever C. 

Distances D.D.D. B. give diameters of space circles or the distances that the 
valves move apart, and the distances of D from the centre are the actual half 
travels of expansion valve. 



40 



GOVERNORS AND GOVERNING MECHANISM. 




11 AUTOMATIC " SLIDE VALVE GEAR. 



41 




42 GOVERNORS AND GOVERNING MECHANISM. 

lowering or raising it. Fig. 22 is an example of this class 
of gear and is described as follows : 

The valve gear consists essentially of an ordinary main 
slide valve A, of box section, having the usual steam ports 
and exhaust cavity on the front side, and two sets of 
inclined ports in the back, each giving admission to that end 
of the cylinder to which it corresponds. 

The expansion slide valve B has two sets of inclined ports 
corresponding to the above inclined ports on back of main, 
and slides on a crossbar C in the steam chest, connected 
through a stuffing box to the governor D. 

The main and expansion slide valves are separately driven 
direct from two eccentrics M. and E. keyed on the crank 
shaft ; the main valve spindle is connected direct to the 
main valve, the expansion valve spindle being connected to 
the frame F, on which the expansion valve is free to slide in 
a direction at right angles to its motion. 

Action. — The main and expansion slide valves have always 
the same relative travel. 

The governor regulates the position of the expansion valve 
crosswise on the back of the main, and so moves the edges 
of the inclined ports nearer to or farther from the inclined 
ports in the back of the main valve. When the governor 
rises, the distance between the cutting off edges is diminished 
and steam is cut off earlier ; when the governor falls the 
distance is increased, and the cut-off takes place later. 

The bottom section on fig. 22, shows the expansion valve 
in its highest position when the distance between the cutting 
off edges is a minus quantity giving a positive lap, and the 
cut-off is at 0, of the stroke. The other views show the 
governor and expansion valve in its lowest position when the 
distance between the cutting off edges is a positive quantity, 
giving a negative lap, and the cut-off is at ^ of the stroke. 

The following table gives a summary of the above methods 
of obtaining variable expansion by means of a slide or slide 
valves. (Table, fig. 23.) 

In all the above it will be seen that the governor in order 
to vary the cut-off, has to change the position of the valve in 
relation to its driving mechanism, or, in other words, to do 
the work of shifting the valve on its face. The work to be 



" AUTOMATIC " SLIDE YALYE GEAR. 



43 




Cj q 



44 



GOVERNORS AND GOVERNING MECHANISM. 



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AUTOMATIC TEIP VALVE GEAR. 



45 



done is usually very considerable, and necessitates a very 
powerful governor. 

Fig. 24.— Table of Powers of Some Hartnell Type Governors with a 
Variation of 8 Per Cent. 



2£g 


<o o 

as 

be 


Revolut 


ions per 


minute. 


a 

o 

H 


ft 

s 


Total ft. -lbs. to 

open balls speed 

rising from zero to 

max. 


f 

't.-lbs. 
from 
ax. 


Size of 
ports for 801 
square inch 
pressure. 


Min. 


Mean. 


Max. 


Power ( 

governor — 1 

speed rising 

min. to m 
















A. 


B. 


5" X |" 


3iin. 


278*4 


290 


301-6 


8% 


61" to 121" 


27 


10-9 


6" x r 


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268*8 


280 


291-2 


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49 


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251 


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56 


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216 


225 


234 


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111" to 23" 


270 


101 



. C max. + C min. 



x (r max. - r min.), sometimes given as power of governor. 



C max. - C min. 



x (r max. - r min.) 



(C = cen. force, r = rads. of path of balls in feet.) 

The above table gives the power of some Hartnell type 
governors for different sizes of steam port and steam 
pressures, with percentages of variation. (Table, fig. 24.) 



CHAPTER XII. 

Automatic Trip Valve Gear. 

In this class of valve gear the varying cut-off is obtained by 
causing the valve to be released or disconnected from its 
mechanism at varying periods of the stroke, allowing the 
valve instantly to close, it having been opened against a 
resistance as that of a spring, weight, or vacuum. This gear 



40 GOVERNORS AND GOVERNING MECHANISM. 

is generally used in connection with Corliss valves, or in 
connection with valves of the Sulzer type, but is also used 
in connection with slide and gridiron valves. 
Trip gears are of two classes, viz. : — 

(a) Gears in which the release of the valve from its 
mechanism can only take place when the valve is moving in 
the opening direction, leaving the catch loose to be put into 
engagement by its own weight or a spring at the commence- 
ment of the next stroke. (Examples, figs. 25 and 26.) 

(b) Gears in which the release takes place at any time, 
whether the valve is moving in an opening or closing 
direction, and in which the catch has a positive movement, 
compulsorily bringing it back into engagement at the 
commencement of the next stroke. (Examples, figs. 27 
and 28.) 

The advantages of the latter class of trip gears over the 
former are many, chief amongst them being, first, that they 
permit of both steam and exhaust valves being driven from 
the same eccentric without limiting the range of cut-off to 
less than half stroke, as was the case with the early Corliss 
gears. Second, they allow of the engine being ran at a 
much higher speed than do trip gears which rely upon the 
weight of the catch or a spring to bring it back into position 
for re-engagement at the commencement of every stroke. 

In either case the work to be done by the governor in 
adjusting the mechanism to vary the time of release of the 
valve, and thereby the cut-off is yery light, and this in 
itself is a recommendation for the adoption of this class of 
valve gear if an engine is required to run under varying 
loads with very small percentages of variation in speed. 



AUTOMATIC TRIP VALVE GEAR. 



47 




48 



GOVERNORS AND GOVERNING MECHANISM. 







AUTOMATIC TRIP VALVE GEAR. 



49 




5gm 



50 



GOVERNORS AND GOVERNING MECHANISM. 



CHAPTER XIII. 

Positions of Governor Ball and (tear for Different 

Points of Cut-off. 
In designing a governor for any valve gear it is necessary 
to first determine the positions of the gear to give the 
required lap, travel, angular advance or whatever it may be, 
for a number of points of cut-off or angles of the crank, and 
then to find the position of governor ball for these points of 
cut-off. 

These points should not be equal divisions of the stroke, 
Ylz -> h h h I j & c -> sucn as are generally taken in laying 




Fin. 29.— Allen Link. One Slide Valve. 



down the Zeuner diagram • but should be such as will give 
equal divisions of the load, or, what amounts to the same 
thing, equal alterations of mean effective pressures. 

The percentage of the stroke at which the steam must be 
cut off to give a mean effective pressure representing any 
given percentage of the maximum pressure, is given by the 
following table, calculated by the formula given in I). K. 
Clark's Mechanical Engineer's Pocket-book : — 
Fraction of stroke when ( *079 *125 -185 *25 "334 -425 

steam is cut off j -526 *64 765 

Mean effective pressures i 10 20 30 40 50 60 

of maximum ) 



70 80 90 percent. 



GOVERNOR AND VALVE DIAGRAM— SLIDE VALVE. 51 

Figs. 29 and 29a are expanded Zeuner diagrams of link 
and die type valve gears, exhibiting a simple method of 
obtaining the proportions of link, position of die in link, 
and position of governor arm for different loads. 

Fig. 30 shows the same for a valve gear having variable 
lap to expansion valve, but constant relative travel and 
angular advance of eccentrics. The construction of the 
diagram is as follows : — 

On a diagram giving the position and the angular advance 
of the main and expansion eccentrics draw lines representing 




Fu. 29a.— Hartnell Gear. Two Slide Valves. 

the angles of the crank for the different points of the stroke 
at which the steam is cut off, and let these points be arranged 
so as to give equal alterations of mean effective pressures, or, in 
other ivords, equal alterations of loxd on the enyine. 

At right angles to the lines representing the angles of the 
crank draw lines through the centre of the main eccentric, 
and on the expansion eccentric centre, touching these lines, 
describe semi-circles above and below the line joining the 
centres of the two eccentrics. The radii of these semi-circles 
above the line will represent negative laps, those below 
positive laps for the different points of cut-off. 

Draw parallel lines touching these lap circles, and the 
distances between them will represent alterations of lap for 



52 



GOVERN ORS AND GOVERNING MECHANISM. 



the different points of cut-off. If the expansoin valve 
port edges are at an angle of 45 deg., then these distances 
will also represent alterations in height or lift of the valve, 
and these again may represent the lift of the governor. 

With a radius in the same proportion to the governor arm 
as the lift of the valve is to that of the governor, describe 
an arc on the lines of lift, and from the points of its inter- 
section with them draw lines to the centre. Lines from the 




4«6iCS or Gcv v 4R»i 




1>*t CQu/\i_ /^tfitfitnr^ (, Lcho 




Fig. 30. — Trapezium Gear. 


Two Slide Valves 



same centre at an angle to these equal to that of the gover- 
nor arm will give the position of the governor arm and ball 
for the different points of cut-off. 



Positions of Governor Ball for Trip Gears. 

Fig. 31 is a diagram of a trip gear of the type shown in 
fig. 26, page 47, giving the position of gear, shape of trip 
cam, and lift of governor for different loads. 

The construction of the diagram is as follows : — 

On a diagram giving the centres of motion of levers, 

direction of eccentric rod and centre of governor lifting 

lever spindle ; on the line of direction of motion of 

eccentric rod, describe a circle representing the travel of the 



GOVERNOR AND VALVE DIAGRAM — TRIP GEAR. 53 

eccentric, and on this mark off the position and angular 
advance of eccentric. 

From the commencement of the stroke, which is 
measured along the line of angular advance of eccentric, 




mark off the different points of the stroke at which the 
steam must be cut off, in order to give equal alterations of 
mean effective pressure, or, in other words, equal alterations 



54 GOVERNORS AND GOVERNING MECHANISM. 

of load ; and from the centre of circle draw radial lines 
representing the angles of the crank. 

On the line of direction of motion of eccentric rod, 
describe the valve circles cutting the lines representing the 
angles of the crank. 

Mark off above and below the centre line of motion of the 
valve lifting links, the distances cut off by these valve 
circles, thus giving the position of links and lever for the 
various points at which steam is required to be cut off. 

Transfer these distances to the arc of the circle described 
by the roller on tail end of hanging trip piece, and from the 
centre of governor lifting-lever spindle describe arcs of 
circles passing through these points. 

Next, from the same centre draw radial lines representing 
the lifts of the governor lever for equal alterations of speed 
and a curve drawn through the points of intersection of the 
arcs of circles with these lines, gives the shape of cam 
required to cause the trip to take place at any part of the 
stroke corresponding to position of governor. 



CHAPTER XIV. 

Positions of Governor Ball for Different Speeds 
within the Total Variation. 

The next thing to do in designing a governor is to find the 
position of governor ball for equal alterations of speed 
within the total variation, and to so arrange that these 
shall correspond, if possible, with the different positions of 
governor ball required for the equal alterations of load. 

Let the total variation be 2 per cent, and the number of 
points of cut- off or positions of the governor be taken as 5, 
then for the governor to be regular the variation between 
each of these positions should be quarter of 2 per cent, or *5 
per cent. The centrifugal force of the balls in each of these 
positions, and at these speeds should next be calculated, and 
the governor loaded accordingly. 

Fig. 32 is an example of the loading of a governor of 
the type shown by fig. 9, page 21. 



GOVERNOR AND SPEED DIAGRAM. 



55 



Fig. 33 is an example of a Hartnell governor, as shown 
in fio\ 8, page 20 ; fig. 34 speed and load carve for the same. 

Positions"for the sleeve or balls for eqnal alterations of 
speed in various types of governor can be found as above, 




&95F7.D>*. 

. ji9OI0Ft.Du. 



-fT 



Fig. 32. 



positions required by the 
obtained by the methods 



and these compared with the 
various types of valve gear as 
explained already. 

It will be found impossible in practice always to so load 
any governor that it will run w r ith equal alterations of speed 



56 



GOVERNORS AND GOVERNING MECHANISM. 



for the positions required for equal alterations of load by 
any valve gear, but by a careful selection a governor may 



fiklN Wrz> . 9 SO 

ff/fe/VCf 8fr*,ff** **n.srrior*& 



Bfr, 



>' r k 1 



i>" * 3'* .3 - 

- 3T %,ju? . 3 ■ 

■ A? & $? . g . 
Tor At S*R< qricn « ^% 




a « 
















Fig. 


33. 






















2n 




















Q 

in 










































>; 






















<dO 














0! 


& 




1 5 






















do 








lo. 


*o 


































la 


1 







Fig. 34. 



always be found, the movements of which approximately 
agree with the movements of the valve gear. 



THE CRANK SHAFT GOVERNOR. 



57 



CHAPTER XV, 

The Crank Shaft Governor. 

The crank-shaft governor was invented as far back as 
1S68, when Messrs. Robey, of Lincoln, applied a ball 
governor, placed horizontally, on the crank shaft of an 
engine to Dodd's wedge motion for shifting the eccentric, 
thereby obtaining auto-expansion with one slide valve 
having variable travel and angular advance of eccentric, but 
constant lap. 

Fig. 35 shows Robey's adjustable eccentric, worked by a 
ball governor and Dodd's wedge motion. 

In designing a shaft governor there are four main points 
that should be taken into consideration over and above 
what has been said in the previous chapters in regard to 
governors generally. 




Fig. 35. 

1. On account of the power of a governor depending 
more upon the speed than upon the weight of the balls, as 
was explained previously, the crank-shaft governor is not 
suitable for engines running at less than, say, 200 revolu- 
tions per minute. 

2. From its peculiar arrangement on the crank shaft of an 
engine, which lays horizontally, the governor must be a pure 
spring loaded governor, and should be arranged in such a 
way that its parts are unaffected by gravity. 

3. The parts should also be arranged in such a way that 
they are as nearly as possible unaffected by inertia forces, 



58 GOVERNORS AND GOVERNING MECHANISM. 

due to change of speed, unless it is intended to utilise such 
forces to operate the governor as in the case of the 
iuertia governor to be described in the next chapter. 

4. The attainment of perfect balance of the revolving- 
parts in a shaft governor is not so simple a matter as it is in 
the case of an ordinary upright governor, and yet on 
account of the governor being used on high-speed engines 
only it is a matter of even greater importance. 

The shaft governor is used both as a throttle valve 
governor as vshown in fig. 10, page 22, and as an automatic 
governor, as shown in fig. 14, page 35. 



CHAPTER XVI. 

The Inertia Governor. 

It was said in a previous chapter that centrifugal force was 
that on which almost all governors depend for their action ; 
but there is another force which may be, and has been, 
taken advantage of to bring about a change in the position 
of the balls in a governor. 

This force is that due to the inertia of a revolving body 
apart from its centrifugal force. 

In all the governors considered in the previous chapters the 
balls are connected to the driving spindle in such a manner 
that they must turn with it, and any increase or decrease in 
speed of the spindle, and, consequently, of the engine, is 
transmitted immediately to the balls. 

They are only free to move in a direction outwards from 
the spindle and to describe a larger or smaller radius ; 
always, however, turning with the same angular velocity as 
the spindle. 

Conceive, now, that the balls of a governor are connected 
to the spindle in such a way that at the same time as they 
have a movement outwards from the spindle they are con- 
strained to turn around it to a small extent, in a direction 
contrary to that in ivhich they revolve. 



THE INERTIA GOVERNOR. 59 

Then the driving force of the spindle, in tending to drive 
the balls, will be resisted by their inertia, and any increase 
in speed of the spindle will not be transmitted immediately 
to the balls. 

Some of the force which would have been expended in 
increasing the speed of the balls will, instead, have been 
spent in tending to open them ont ; while the increase 
of centrifugal force which would have acted to do this, had 
the increased speed of the spindle been immediately trans- 
mitted to the balls, is lost and does not come into play until 
the balls have acquired the increased speed of the spindle. 

It may be here mentioned that the force which has acted 
to open out the balls, and which is measured by the resist- 
ance it meets with in their inertia, acted only during the 
change of speed ; also that the increase of centrifugal force 
which otherwise would have acted, would continue to act, and 
does act after the change of speed has been effected. 

Let the weight of the balls in an inertia governor be 10 lb. 
and the radius of the path described by them be from 3 in. to 
6 in. ; also let the speed increase from 300 to 303 revolu- 
tions per minute, or 5 to 5*05 revolutions per second. 

W v~ 
The energy, viz., - — stored up in the balls when 

revolving at the larger radius and at a speed of 303 

revolutions per minute or 5*05 revolutions per second is 

39*25 ft. lb. ; and that stored up in the balls when revolving 

at the smaller radius, at a speed of 300 revolutions per 

minute or 5 per second, is 9 '6 ft. lb. 

Then the work done by the force which has acted during 

the change of speed against the inertia of the balls in tending 

to open them out is represented by 39 *25 - 9 *6 = 29 *65 ft. lb. 

W v - 

The centrifugal force, viz., exerted by the balls when 

yr 

revolving at the larger radius at a speed of 303 revolutions 
per minute or 5*05 per second is 1571k And the centri- 
fugal force exerted by the balls when revolving at the 
smaller radius at a speed of 300 revolutions per minute or 5 
per second is 77 lb. 



00 GOVERNORS AND GOVERNING MECHANISM. 

The increase of centrifugal force would have been 80 lb., 
and the mean of this multiplied by the distance through 

80 
which the balls have been moved, viz., — x ■ 25 = 10 ft. lb. 

Thus the work done by the force which has acted during 
the change of speed against the inertia of the balls in tend- 
ing to open them out is much greater than that which 
would have been done by centrifugal force. 

But the force which has acted to produce this greater 
quantity of work depends on the time during which it has 
taken to act, or, in other words, during which the change of 
speed has taken place. 

It is possible for the change of speed to take place so 
slowly that this force becomes inappreciable, and therefore of 
no value in opening out the balls of a governor. 

Let the change of speed in the governor at present under 
consideration take place in one second, that is, while the 
governor is making approximately three revolutions. 

What is the force that, acting for one second on a 
weight of 101b., will produce an acceleration corresponding 
to this change of speed, viz., 15*85 - 7*85 = 8 ft. per 
second % 

If the acceleration had been 32*2 ft. per second, then the 
acceleration would be that which would have been produced 
by gravity, viz., the weight's own weight in falling for one 
second. 

But this acceleration is only 8 ft. per second, or one 
quarter that produced by gravity ; therefore, the force 
required to produce it would be only one quarter the 
weight, viz., 2 J lb. 

And the space described by a weight, already moving at 
the rate of 7*85 ft. per second, in acquiring an added 

velocity of 8 ft. per second, is - 11*85 ft. 

This 11-85 ft. x 21 lb. = 29-62 ft. lb., as before. 

Now, let the change of speed take place in two seconds, 
then the mean force acting would be 1 \ lb. ; in three seconds 
•625 lb., and so on. 



THE INERTIA GOVERNOR. 



61 



For the mean force to amount to as much as the mean 
centrifugal force, which would have acted, viz., 401b., the 
change of speed would have to take place in yg-th of a 
second. 

In constructing the inertia governor it is usual to con- 
siderably reinforce the inertia of the balls by the addition of 
other revolving weight. 

Let the inertia of the balls in the governor under con- 
sideration be reinforced by the addition of other revolving 




Ftg. 36. 



weights to the extent of, say, 16 times = 1601b. Then the 
force acting to produce an acceleration of 8 ft. per second in 
one second would be equal to 16 x 2*5, viz., 401b. 

Thus, if it is required that the force acting in an inertia 
governor, when, the change of speed takes place is one 
second, shall be equal to the centrifugal force due to the 
weight of the balls, the total weight in the governor, 



62 GOVERNORS AND GOVERNING MECHANISM. 

revolving at the same radius as the balls, must equal 16 
times that of the balls alone. 

The idea of the inertia governor was first embodied by 
Siemens, previous to the year 1866, in his differential 
governor. 

Siemen's differential governor is described by Goodeve, 
who says : — 

"The chief peculiarity of the differential governor con- 
sists in the fact that the ivhole energy stored up in the 
revolving balls is ready to act upon the steam valve at the 
first instant that the engine attempts to vary from the 
pendulum, whereas in the ordinary governor the additional 
energy stored up in the balls by increased velocity of rota- 
tion is the power available to control the valve. 

" One action is slow and comparatively feeble, the other is 
instantaneous and cannot be resisted." 

Fig. 36 is an example of an inertia governor. Up to the 
present the application of this principle seems to have been 
confined to the crank-shaft governor, but there seems to be 
no reason why it should not be applied to any ordinary 
upright governor, the load or the counterpoise being made 
to serve the purpose of inertia weight. 



CHAPTER XVII. 

Gas Engine Governors. 

While the steam engine governor depends for its action on 
a general change of speed of the engine, and should not be 
affected by the momentary change of speed, or what has 
been called the jerkiness of the engine, the gas engine 
governor, on the contrary (as usually constructed), depends 
entirely for its action on this momentary change of speed or 
jerkiness of the engine. In fact, the greater the momentary 
change of speed, the greater the action of this governor in 
cutting out more impulses to reduce the power of the 
engine to suit its lighter load. 



GAS ENGINE GOVERNORS. 



63 



Thus : In a gas engine governed in the usual way, i.e., on 
the hit and miss principle, the less the load the more un- 
steady will be the running of the engine. 

Figure 37 shows a centrifugal governor as applied to gas 
engines made by Messrs. Crossley. Its action is as follows : 
At every firing stroke of the engine the governor G rises and 
lifts the flat plate P suspended from the lifting levers, from 
between the plate V on the gas valve lever and the head of 
the gas valve spindle S. 



V- 





Fig. 37. 



At full load the fly wheel prevents the impulse given by 
the firing stroke from causing the momentary speed, and 
consequently the governor, to rise too high; therefore, by the 
time the cam C is ready to operate the lever L, the plate P 
is again in position between the plate on the gas valve lever 
and the head of the gas valve spindle. Should the load on 
the engine, however, be diminished, the impulse of the firing 
stroke causes the momentary speed and, consequently, the 
governor to rise so high that by the time the cam is 



64 



GOVERNORS AND GOVERNING MECHANISM. 











c 



2 



fe ^" 






§2 






C O 



^b 



GAS ENGINE GOVERNORS. 



65 



ready to operate the lever L the plate P is not again in 
position, and the lever fails to open the gas valve S until 
such time as the speed has fallen to that at which the 
governor runs in its normal position. 







Fig. 39. 



The governor is a dead-weight governor, but the sleeve is 
not in contact with the counterpoise until the engine has 
reached a certain speed, thus enabling the sleeve to rise 
quickly as the engine gets up speed. When the normal 
speed is reached, the governor begins to operate as just 
described. 
6gm 



66 GOVERNORS AND GOVERNING MECHANISM. 

Fig. 38 is a diagram showing the cycle of operations for 
an Otto Cycle Gas Engine at various loads, also showing the 
necessary fluctuations in the speed of governor and engine. 

This principle of action of the gas engine governor depend- 
ing, as it does, on a continual series of sudden bounds (the 
less the load the greater the bound), enables another form 
of force, viz., inertia, to be satisfactorily taken advantage of 
in the operation of a gas engine governor. 

Fig. 39 shows an inertia governor, as applied to gas 
engines, made by Messrs. Crossley. Its action is as follows : 
The cam C operates the lever L, the roller on which is held 
hard against the cam by the spring S. On the lever L, 
which also operates the air valve, is pivoted at J the governor 
weight G, and this is prevented, when the engine is iimning 
at full load, from being left behind the lever L by the spring 
K. To lever L is attached the striker plate P. 

The spring K is so adjusted that when the load on the 
engine is diminished the comparatively greater impulse of 
the firing stroke, acting against the inertia of the weight G, 
causes it to be left behind, the striker P then missing the 
gas valve T until the speed again falls to the normal. 

A more satisfactory form of governor for gas engines, con- 
sidered with a view to obtaining regularity of speed merely, 
would be one that operated on the same lines as the steam 
engine governor, viz., admitting a larger or smaller amount 
of a previously mixed charge to the combustion chamber at 
every charging stroke. 



CHAPTER XVIII. 

Relay Governors. 

The previous chapters have dealt with governors acting on 
the simple principle of the Watt governor, which is, that 
when the greater demand made on the engine for power 
(which occasioned the fall of speed and, consequently, the 
greater opening of throttle valve) is maintained^ the fall of 
speed must also be maintained, and vice versd. 



RELAY GOVERNORS. 67 

But if, when the greater demand is made on the engine 
for power, occasioning a fall of speed, and consequently a 
greater opening of throttle valve, some other agency, apart 
from that of the engine itself, be introduced to regulate the 
length of connections between governor and valve, then the 
greater opening of throttle valve occasioned by the fall of 
speed may be maintained without the governor having to 
remain in its lower position or the engine having to continue 
running at its lower speed, and vice versa. 

This is the principle of the relay, auxiliary or supple- 
mentary governor. 

Fig. 40 shows an example of a relay governor, provisionally 
protected by the writer, in which the agency employed to 
regulate the length of connections between governor and valve 
consists of the momentum and inertia stored up in a revolving 
wheel. It will be noticed that the inertia of the revolving 
wheel, in this case, is not used as it is in the ordinary 
inertia governor, to open out the balls, but is introduced to 
regulate the length of connections between governor and 
valve, the governor itself remaining to all intents and 
purposes a simple ordinary centrifugal governor. With this 
difference, however, that, instead of rising or falling as the 
speed of the engine rises or falls, it simply tends to rise and 
fall — this tendency forming the resistance against which the 
momentum or inertia of the flywheel acts in order to effect 
the alteration in the length of valve rod to give a greater 
or less admission of steam to suit the altered demand made 
on the engine for power. 

It will be seen that — 

1. No change can be made in the load on the engine 
without a change of speed of the governor tending to make 
it rise or fall, and making it run faster or slower than the 
loose flywheel ; and 

2. No change can take place between the speed of the 
governor and the speed of the loose flywheel without an 
adjustment being made in the length of the valve rod, 
immediately bringing back the engine to its proper speed, 
viz., that at which the governor has no tendency to rise or 
fall. 



68 



GOVERNORS AND GOVERNING MECHANISM. 




Fig 40. 



RELAY GOVERNORS. 



69 



A is the governor pure and simple, carried on a spindle 
driven by bevel wheels B B, from the engine in the ordinary 
way. C is a forked bell-crank lever, taking the place of the 
usual lifting levers, and connected direct to the throttle 
valve or valve gear by the rod D. E is a second bell-crank 
lever, which carries on one end the aforesaid bell-crank lever 
C, and by its movement effects a virtual alteration in the 
length of the rod D. F is an internally screwed sleeve, 
screwing on to the governor spindle and revolving with it, 
being prevented from screwing up or down by the fork end 
of lever E. 

G is a feather on the outside of sleeve F, causing it to 
turn with the bevel wheel H through the boss of which it 




Fig. 41. 



Fig. 42. 



slides. J is a small flywheel, carried in a bracket bolted to 
the governor stand, and is geared to the sleeve F by bevel 
wheels H H. 

As the governor rises (speed accelerating) it screws up the 
end of lever E, and brings the bell crank into position 
(shown in fig. 41), altering the position of rod D, and closing 
the throttle valve. 

As the speed falls the governor screws down the end of 
the lever E, and brings the bell-crank levers into position 



70 



GOVERNORS AND GOVERNING MECHANISM. 



(shown on fig. 42), altering the position of rod D, and open- 
ing the throttle valve. 

It will be noticed that the governor, after it has reached 
its proper speed, remains at the same height, and conse- 
quently runs at the same speed in both positions. 

Fig. 43 is another arrangement of the same governor. 




Fig. 43. 

Fig. 44 shows the Knowle's supplementary governor, 
constructed by Messrs. Hick, Hargreaves and Co., in which 
the agency employed to adjust the length of connections 
between the governor and valve consists of the centrifugal 
force of another governor. 

The sleeve of this supplementary governor is provided 
with an upper and lower flange, between which is placed a 
small friction wheel, running on a spindle. On the other 



RELAY GOVERNORS. 



71 



end of this spindle is a grooved pulley which drives, by 
means of a cord, a similar pulley on the adjusting nut 
connecting the two ends of the rod between the main 
governor and valve. 

On the governor tending to rise or fall, it turns the 
friction pulley in one direction or the other, and so 
operates the adjusting nut, shortening or lenthening the con- 
nection between main governor and valve. 

In calculating the loading, &c, of this class of governor, 
a variation of speed must be allowed for just as in the case 




Fig. 14. 



of an ordinary governor, as it is from this that the governor 
derives its power. 

Instead of the variation being permanent, however, as in 
the case of an ordinary governor, it is in this case merely 
momentary. 



72 GOVERNOKS AND GOVERNING MECHANISM. 



APPENDIX I. 



Governor Power. 

" That governor, therefore, had the greatest lifting and 
forcing poiver which, when revolving at a speed corresponding 
to its lowest position, ivould require the greatest force to make 
it take up the highest position at the same speed, and, con- 
versely, ivhen revolving at a speed corresponding to its highest 
position, woidd require the greatest force to make it take up the 
lowest position" — J. Richardson, in reply to discussion on 
his paper on " The Mechanical and Electrical Regulation of 
Steam Engines." Proc. Inst. Civil Engineers, vol. cxx., May, 
1895. 

The writer has found that widely different notions are held 
by different engineers as to what may be taken to be the 
power of a governor. 

In the preceding pages the power of a governor is 
taken to be the mean difference of the centrifugal force at 
the governor's top and bottom speeds multiplied by the 
range, and not the mean total centrifugal force multiplied 
by the range which is taken by some to be the power of a 
governor, but which is the " total stored energy." 

Of course, what is meant by the power of a governor is its 
" power of overcoming external resistances," and a little 
consideration will show that while the li total stored energy " 
in a governor may be very great, yet very little or none of 
this may be available for the power or purpose mentioned, 
viz., that of overcoming external resistances. 

Let anyone try to lift the governor of a steam engine by 
a lever fixed to the lifting spindle before the engine has 
reached its proper speed, and he will find it hard ; but let 
him try after the engine has reached its proper speed, and 
he will find it easy. 

Let him hold the lever down after the engine has reached 
its proper speed, allowing it to run still faster, then loose 



APPENDIX. 73 

the lever gradually, the balls opening out against the pull 
of bis hand, until they have taken up the position due to 
their top speed ; the external work done by the governor 
wiU be the pull he was exerting multiplied by the distance 
through which that pull acted, and this is the power of the 
governor to overcome external resistances. (It is assumed 
for the moment that the governor has no valve gear, etc., to 
lift.) 

Now let the steam be shut off and the governor still 
supported in its top position after the engine has stopped^ 
then gradually lowered ; the pressure exerted in doing this, 
multiplied by the distance through which it was lowered, 
will be equal to the total stored energy, or the total work 
which was done by the governor in lifting through its fall 
range of movement. 

The work done in compressing a spring is equal to the 
mean force exerted multiplied by the range through which 
it acts ; and this is the total work done by a spring-loaded 
governor in lifting through its fall range of movement. 

Also the work done in lifting a dead weight is the weight 
multiplied by the height through which the weight is 
lifted ; and this is the total work done by & dead-weight 
loaded governor in lifting through its full range of move- 
ment. 

But this is not the power that can be given out by a 
governor when running between its top and bottom speeds. 

In a steam engine the mean of the pressures on the two 
sides of the piston, multiplied by the distance through 
which the piston is moved, would not be the power of the 
engine ; neither would the mean of the tensions on the tight 
and slack side of a belt over a pulley, multiplied by the 
movement of the belt, be the power transmitted by a belt. 

The power transmitted in either case would be the mean 
of the difference of pressures or tensions multiplied by the 
distance moved through. It may be taken that while the 
forces in a governor are balanced, it can have no power 
of overcoming external resistances, in the same way as it is 
taken that while the forces or steam pressures on either side 
of the piston of a steam engine are balanced, it can have 
no " power." 



74 GOVERNORS AND GOVERNING MECHANISM. 

What is required in order that a governor may have 
"power" (supposing the forces to be already existing, viz., 
the centrifugal force balancing the resistance of the spring 
or weight) is that the balance shall be upset ; in the same 
way as for an engine to have power, it is required that the 
pressure on the ore side of the piston must be greater than 
that on the other. 

The way in which the balance of pressures or forces in a 
governor is upset is by an increase or decrease of speeo. 
And the amount by which it may be upset depends on the 
amount by which the speed may be increased or diminished ; 
or, in other words, depends on the variation of the governor. 

The power of a governor, then, may be defined as the un- 
balanced force capable of being generated in a governor by a 
given change of speedy multiplied by the distance through which 
this unbalanced force can act. 

With a given variation, what is the amount by which the 
balance of forces in a governor can be upset ? 

Let a governor be running with its balls in their top 
position at its top speed, say, 303 revolutions per minute, 
and let the spring in the governor, in balancing the 
centrifugal force due to this speed, be exerting a force of, 
say, 100 lb., then while the governor continues to run at this 
speed it is exerting no power in the sense of overcoming 
external resistances. 

But let the speed be suddenly reduced to the minimum, 
say, 300 revolutions per minute, at which it would be exert- 
ing a centrifugal force of, say, 80 lb., then the governor can 
exert force and do work in overcoming external resistances 
until the balls fall and the pressure exerted by the spring is 
80 lb., balancing the centrifugal force of the governor running 
at its lower speed with the balls in their lower position. 

Again, let a governor be running with the balls in their 
lower position, at a speed of 300 revolutions per minute, the 
spring in the governor exerting a force of 80 lb., equal to the 
centrifugal force due to this speed ; then, while the governor 
continues to run at this speed, it is exerting no power in the 
sense of overcoming external resistances. 

But let the speed be suddenly increased until the governor 
is exerting a centrifugal force of 100 lb., then it can exert 



APPENDIX. 75 

force and do work in overcoming external resistances until 
the balls open out and the pressure exerted by the spring 
is 1001b., balancing the centrifugal force of the governor 
running at its top speed with the balls in their top 
position. 

Let the range of this governor be 2 inches, then the work 
that may have been done by the governor against external 

.100-80 . OA . „ 

resistances is x 2 in. - 20 in. lbs. 

2 

But the total stored energy when the governor was running 

100+80 . 1QA . „ 

in its top position was - — — — x 2 in. = lbOin. lbs. 

Now, let the variation be increased so that the 
centrifugal force varies from 601b. to 1201b., then the 
external work the governor may be capable of doing 

.120-60 . ark . 1U 

is — — - x 2 in. = 60. in. lbs. 

2 

But the total stored energy, viz.: 

x 2 in. = 180 in. lbs., is still the same. 



76 GOVERNORS AND GOVERNING MECHANISM. 



APPENDIX II. 



Examples of Governors and Governing Mechanism by 
various Makers. 

Note. — The following illustrations and particulars have 
been kindly supplied by the editor of The Practical 
Engineer : — 

I. HartnelVs Patent Automatic Expansion Gear. — Fig. 45 
shows this governor and gear as made by Messrs. Marshall, 
Sons and Co. Limited, Gainsborough, and is described by 
them as follows : — 

" This arrangement consists of a highly sensitive and 
powerful governor, of special construction, acting through a 
link and die on to an expansion cut-off valve working at the 
back of the main slide valve ; the ordinary throttle valve is 
dispensed with, and the speed of the engine thoroughly 
controlled by means of the expansion valve, which regulates 
the admission of steam into the cylinder exactly in propor- 
tion to the duty performed by the eDgine. 

" This gear is very simple and most reliable in its action, 
automatically regulating the speed with every varying load, 
and is thoroughly adapted for either heavy or light work. 
Engines equipped with this governor develop more power 
with greater economy in fuel than if fitted with throttle 
valves in the usual way." 

Messrs. Marshall have now over 3,900 engines at work 
with this gear, with very satisfactory results. 

II. Galloivay's Patent Parabolic Governor and Automatic 
Gear. — This gear, illustrated by fig. 46, consists of the 
makers' well-known parabolic governor acting through an 
Allen link to give a varying cut-off, by varying the travel 
and angular advance of a single slide valve. Fig. 47 is a 
clearer view of the governor itself. The engine is fitted 
with separate exhaust valves operated by a fixed eccentric, 
giving constant compression and release, which cannot be 



APPENDIX. 



77 



obtained when this mode of governing — viz., by varying 
travel and angular advance — is applied to a single slide 
valve, which also controls the exhaust. 

This system has all the advantages of the two-slide 
valve gear. 




Fig. 45. 



III. Tangye-Johnson Automatic Gear.— This gear, illus- 
trated by fig. 48, is an " automatic " slide-valve gear, but 
differs from any of those described in the preceding pages 
in that the varying cut-off is not obtained by any ordinary 
action of the slide valve, such as variation of lap, travel, or 



78 GOVERNORS AND GOVERNING MECHANISM. 




Fig. 47. 



APPENDIX. 



79 



angular advance, but by the rocking action of the back part 
of the valve, which is hinged so as to close first the port in 
the back of the valve communicating with one end of the 




Fig. 48. 



cylinder and then the other, as it comes in contact with one 
or other of a pair of right and left-hand cams fixed on a 
spindle lying in the direction of motion of the valve. 



80 



GOVERNORS AND GOVERNING MLCHANISM. 



This spindle is connected, by a lever, with the governor, 
which, on rising or falling turns it, bringing the parts of the 
cams, which are nearer or further apart, into line with the 
rocker, causing it to close the port in the valve earlier or 




Fig. 49. 

later, according to the time at which it comes in contact 
with the cams. 

In this gear there is no sliding cut-off valve on the back 
of main to cause additional friction, or any second eccentric 
with its rods and link work, and yet it has the advantages 



APPENDIX. 



81 



of the two-slide valve gear in that the exhaust is not inter- 
fered with. 




2 



IV. Proell Automatic Expansion, Apparatus.— This 
apparatus, manufactured by Messrs. Isaac Storey and Co., 

7gm 



82 



GOVERNORS AND GOVERNING MECHANISM. 



and illustrated by fig. 49, consists of a single drop valve 
controlled by Prodi's patent governor. 

The valve, which is an equilibrium valve, is opened twice 
during every revolution by the rock lever, shown in the 




Fig. 51. 



illustration, worked by an eccentric from the engine shaft, 
and is "closed by a spring on being disengaged from the 
lifting lever, which disengagement occurs earlier or later in 
the stroke, depending on the height of the governor. 



APPENDIX. 



83 



The apparatus is provided with the usual dash pot, which 
enables the valve to be closed without shock. 

This apparatus is used in connection with an ordinary 
slide valve, which distributes the steam to either end of the 
cylinder and also opens and closes the exhaust, or it may be 
used with a special form of Corliss distributing valve, 
worked by another eccentric, as shown in the illustration 

fig. 50. 

Fig. 51 is an illustration of the governor used in 

connection with this apparatus. 

This governor is arranged so that the balls move through 
equal distances with equal alterations of speed, also the arms 
of the governor are arranged in such a way that the balls, as 
they open out, remain in the same horizontal plane. 

V. FroelVs Patent Two-Valve Releasing Gear.— Fig. 52 
shows this gear as made by Messrs. Marshall, Sons and Co. 
Limited, Gainsborough, and is described by them as 

follows : — 

"The illustration represents a section of a cylinder fitted 
with Proell's patent two-valve gear. This gear consists 
of two equilibrium admission valves A, one to each end of 
the cylinder. These are alternately lifted by means of the 
valve spindle in connection with the principal trip levers B. 
These trip levers are depressed by means of the L levers C, 
which are connected on opposite ends of the rocking lever 
worked from the eccentric. The ends D of the L levers, 
projecting towards the centre, are brought into contact at 
each stroke with the trip pad E. This trip pad is connected 
with the governor through the medium of the levers F and G 
and the shaft H ; and the height of this trip pad determines 
the moment of cut-off of the steam, for as soon as the end D 
of the L lever reaches the trip pad any further movement 
of the rocking lever disengages the L lever from the trip 
lever B and the valve immediately closes. The closing speed 
of the valve can be very readily regulated by means of the 
spring box K, so that although it closes the valve very 
rapidly, it does it very quietly, thus preventing any undue 
wear of the valves or faces. 

" All the working parts of this gear are case-hardened and 
the cutting-off edges are made of tool steel hardened. 



84 GOVERNORS AND GOVERNING MECHANISM. 





APPENDIX. 85 

" The governor controlling this gear is of a very powerful 
and sensitive type, and has sufficient range to regulate the 
cut-off at any point up to five-eighths of the stroke. It can 
be fitted with a special adjusting arrangement, so that the 
speed of the engine may be varied 5 per cent either way 
whilst the engine is running ; this is a point of considerable 
importance for many classes of work, and enables the speed 
of the engine to be most accurately adjusted." 

Fig. 53 shows Messrs. Marshalls' engine fitted with this 
gear and Corliss exhaust valves worked by a separate 
eccentric. 

VI. Richardson-Rowland Patent Drop Valve Gear. — This 
is a two-valve releasing gear, but the valves are operated 
each by a separate small eccentric fixed on a side shaft, 
which lays parallel with the engine, and is driven at the 
same speed as the engine shaft by means of a pair of skew 
gears. 

This expansion gear, illustrated by figs. 54 and 55, is 
made by Messrs. Robey and Co., Lincoln, and is described 
by them as follows : — 

" A A, fig. 54, are the two admission valves, and being 
almost in equilibrium, are lifted with great ease by the 
small eccentric and rods worked from a shaft revolving at 
the same speed as the engine, and parallel with the bed- 
plate. 

"The admission valve is raised at the commencement of 
the stroke and held wide open until the point of the cut-off 
is reached, when it is instantly relieved, and falls on its seat, 
an air cushion in the guide cylinder above preventing its 
falling too heavily. 

"While the valves are alternately raised by the engine, the 
point at which they are dropped depends upon the position 
of the governor, which regulates the cut-off at any point 
from nothing to f of the stroke. 

"BB show the exhaust valves. These are triple-ported so 
as to give a wide opening with a small travel, and work with 
a minimum of friction. Being placed directly under the 
cylinder, this latter is kept perfectly drained, and both 
admission and exhaust valve being close to cylinder body, 
the loss of steam in ports is avoided." 



86 



GOVERNORS AND GOVERNING MECHANISM. 




APPENDIX. 



87 




Fig. 54. 



88 GOVERNORS AND GOVERNING MECHANISM. 

" Referring now to the cross-section of the cylinder, fig. 55 
shows very clearly the whole of the gear for one end of the 
cylinder, it will be seen that the small eccentric rod K is 
enabled to act upon the valve A (which is in equilibrium) by 
depressing the outer end of the lever B, by which the valve 
is raised. 

" This occurs just before the commencement of the stroke. 

" Owing to the different arcs described by the end of the 
eccentric rod, and tbe lever B respectively, at a certain 
point the tripper L slips out of contact, and the valve drops 
instantaneously, cntting off the steam supply. 

" The arrangement for securing an automatic cut-off is 
simplicity itself, the governor in rising moves the lever arm, 
and with it the pivot or fulcrum R of lever B, which, of 
course, has the effect of causing the tripper L to lose its 
contact, and the valve to fall at an earlier period in the 
stroke, and thus as the governor rises and falls the point o 
cut-off is accelerated or retarded accordingly. 

" It will be noticed that the long horizontal arm of lever 
is prolonged past the governor, and that a small cord or 
string is attached to it. This cord may be led away to any 
part of the building, and forms a ready means of instantly 
stopping the engine in case of emergency, as in the case of 
accident to life or machinery. By pulling the cord, which is 
done with no more exertion than is required to ring an 
ordinary house bell, the lever G draws the valve-levers B 
completely clear of the trippers, when, of course, no steam 
can enter the cylinders, and the engine, which may have 
been exerting a thousand horse power, may be brought to a 
stand at once by the touch of a child. 

" With so sensitive an apparatus as this, accurate govern- 
ing is easy of attainment, and a small and simple centrifugal 
governor fulfils every requirement." 

VII. Frikart Corliss-Valve Trip or Releasing Gear, — This 
gear, as manufactured until recently by Messrs. Greenwood 
and Batley, Leeds, is illustrated by fig. 56. 

It is of the class in which the release can take place 
whether the valve is moving in an opening or closing direc- 
tion, the trip catches having a positive movement 



APPENDIX. 



89 



compulsorily bringing them back into engagement at the 
commencement of every stroke. 




Fig. 55. 



It is therefore possible to operate the steam valves from 
the same eccentric as the exhaust and yet have a late cut-off. 



90 



GOVERNORS AND GOVERNING MECHANISM. 














>$JK 



fW* 



APPENDIX. 91 

It will be noticed that the engine is fitted with a single 
eccentric and wrist plate for both steam and exhaust valves, 
the motion for the trip catches being derived from the 
vertical motion of the eccentric rod and taking place at an 
opposite time to the motion of the steam valve levers, the 
governor in rising or falling altering the path of the resultant 
compound motion so as to bring the catches out of engage- 
ment earlier or later in the stroke according to the " position" 
of the governor. 

VIII. Hick, Hargreaves' Patent Compensating Steam Bash- 
Pot for closing Corliss Admission Valves is illustrated by 
figs. 57 and 58. 

In describing this gear the makers say : — 

" When the steam admission valves of a Corliss engine 
have been opened to the necessary extent by the positive 
action of the gear, they are disengaged by the trip motion 
controlled by the governor, and require to be closed promptly 
but without shock. The power required to effect this 
depends principally on the friction of the valves on their 
seats, which is proportional to the difference between the 
pressures above and below the valves. The means hitherto 
employed to provide this power have been either vacuum, 
pressure, or spring dash-pots of some definite strength without 
any provision for automatically adjusting their power to the 
resistances to be overcome. For factory engines where the 
minimum load, consisting of the friction of the engine and 
shafting, usually amounts to not less than 20 per cent of the 
full power of the engine, the pressure of steam in the 
cylinder during admission does not vary greatly over the 
whole range of load, and the power needed to close the 
valves being therefore practically constant, it may suitably 
be provided by dash-pots of the character described, some- 
times needing assistance at or near the minimum load by 
throttling the steam supply at the stop valve. On the other 
hand, if the engine is required, as is usually the case 
with engines driving electric generators and some other 
classes of work, to deal with a load which may fluctuate over 
the whole range, from mere friction up to perhaps 50 per 
cent overload, and this with the full steam pressure con- 
stantly on the engine, such dash-pots as described are no 




Fig. 57. 



APPENDIX. 93 

longer capable of meeting the requirements, as the trifling 
pressure of steam required in the cylinder to drive the engine 
at a very light load no longer approaches the pressure in 
the steam chest, and the great unbalanced pressure increases 
the friction between the valves and their seats to such an 
extent as to make the power required to move them four or 
five times as great as at moderate or full loads, and greater 
than the dash-pots can exert. The result is that the valves 
fail to close properly, and the engine runs irregularly and 
may even attain excessive speed if the gear is of a class 
which does not provide for the valves being positively closed 
on the return stroke, if not previously closed by the dash- 
pot. The defect described is common to all types of 
Corliss gear, and has caused some engine builders to employ 
drop valves, which, having no sliding friction, are free from 
this particular difficulty, though open to many other 
objections. 

" The dash-pot shown in the illustrations is designed to 
overcome the difficulty, and does so automatically in the 
simplest possible way by employing the variable pressure 
which causes the varying friction of the valve to act also 
on a piston employed to close it, the result being that the 
power bears a constant ratio to the load. The dash-pot con- 
sists of an upper steam cylinder and a lower air cushion 
cylinder combined in one casting attached to the valve 
bonnet. The steam cylinder contains a simple piston, the 
upper side of which, like the admission valve, is exposed to 
the steam chest pressure, whilst its under side, again like the 
admission valve, h exposed to the cylinder pressure, the 
connections being made by the small copper pipes seen in 
the illustration. The piston rod of the small cylinder is 
made of a larger diameter than needed for mere strength, its 
area, acted on by the difference between the steam chest and 
atmospheric pressures, being made sufficient to overcome the 
constant friction and inertia of the parts, whilst the variable 
and larger proportion of the load is, to use the expressive 
American phrase, ' taken care of by the varjing pressures 
acting on the remaining annulus of the piston. The steam 
cylinder is proportioned to close the valve under its 
maximum coefficient of friction, and the air cushion cylinder 



94 GOVERNORS AND GOVERNING MECHANISM. 

to take up any surplus energy, an air valve of special con- 
struction, capable of fine adjustment, being provided on its 
under side. This form of dash-pot, after more than a year's 
severe trial, has entirely fulfilled the makers' expectation, 
and has recently been fitted by them to five engines of 
from 1,450 to 1,600 I.H.P., one of which has been running 
for some time in a most satisfactory manner at the Leeds 
Corporation Tramway Power Station. It is from a photo- 
graph of this engine that the illustration has been prepared. 

"The valve gear to which this dash-pot is applied is of the 
'Frickart' type, in which the trip is actuated positively by 
a supplementary eccentric instead of by spring action and 
the opening motion of the valve, this securing several 
advantages, including an approach to positive action, allow- 
ing the valve gear to run at a high speed, and a full opening 
of the steam port at a much earlier point in the stroke than 
with Corliss gears of the more usual type. The gear, a 
complete set of which was exhibited at the Glasgow 
Exhibition, is made with very liberal proportions and sur- 
faces, in view of the high speed and heavy loads for which it 
is designed." 

IX. Fraser and Chalmers' Reversing Corliss Engine Trip 
or Releasing Gear. — Primarily this gear consists of the 
steam and exhaust valves driven from the same eccentric 
through an Allan link-motion reversing gear, the cut-off 
being effected by the lap of the valves. To this is added 
the Seymour patent auxiliary cut-off gear, controlled by the 
governor, and giving a range of cut-off extending from zero 
to 95 per cent of the stroke ; the cut-off at both ends of the 
cylinder being even throughout the range, a feature not 
usual with ordinary gears. 

The motion of this gear, which, as in the case of the 
"Frikart," takes place at an opposite time to the motion of 
the steam valve levers, is derived from a separate auxiliary 
eccentric, as shown in sketches, figs. 59 and 60. 

A difficulty in applying any form of automatic governor 
gear to a reversing engine is as follows : — Should the engine 
suddenly be reversed when running at full speed, the 
governor being then in its top " position ? ' and cutting off 
early in the stroke, very little or no steam will be admitted 



APPENDIX. 



95 



to the cylinder to effect the reversal of the engine. The 
effect would be much the same as "back-pedalling" on a 
bicycle fitted with free wheel. 




17 CCC c ROD 



COVZMOfi 
SHAFT 



Fig. 59. 




ROCK INC CAM 

AS GOVERNOR RISES 
THIS IS TWISTED MORE 
& MORE TO THE PlN * 
THEN ROCKS FROM A 
DIFFERENT CENTRE 
& 30 KNOCKS OFF. 



CAM 



Fig. 60. 



The patent Whitmore controller, a very ingenious 
arrangement of grab-hook, however, is fitted to the reversing 



96 



GOVERNORS AND GOVERNING MECHANISM. 



lever when this gear is used, by means of which, when the 
reversing lever is pulled over, a temporary engagement is 
made with a lever on the governor shaft, and the governor is 





-& 



VERSED SINE OF THIS ARC 

GIVES H0RI2 L MOVEMENT TO CRAB HOOK 



Fig. 61. 



pulled down into its lowest "position," allowing the valves 
to admit full steam against the piston. This arrangement 
is shown in sketches, figs. 61 and 62. 

The illustration, fig. 63, shows a Corliss winding engine 
built by Messrs. Fraser and Chalmers for the Sherwood 
Colliery Co., Mansfield, fitted as above. The governor is 
not seen in the illustration, being partly hidden behind the 
near cylinder. 



TO REVERSING LEVER 




-T GOVERNOR SHAFT 



AS COY" RISES LEVER 
TURNS IN DIRECTION 
OF ARROW 



TH/S CAM MAKES IT RISE 6 
SO END OF BEL L CRA N/1 DROPS I A 
CRAB ROOM 



Fig. 62. 

X. Fraser and Chalmers' Combined Air and Speed 
Governor (Whitmore's Patent). — This governor gear has 
been specially designed for air compressors and pumping 
engines. 

"1. Application to Compressors. — The governing of a com- 
pressor does not appear to have had the attention it 




:.:■:■ :^^ 



APPENDIX. 97 

warrants. It is apparent that it is useless to purchase an 
engine fitted with the best kind of valve gear and of first- 
class workmanship throughout in order to obtain the utmost 
economy, if the governing of the engine is at all erratic in 
its action, or if the engine is fitted without a governor at all, 
which is frequently the case in even very large compressors. 
There are, of course, various ways of governing the work of 
a compressor, but we are only considering the means that 
are most efficient. A compressor has to run under a good 
many changes of circumstances. First, regarding the steam 
engine : the steam is probably supplied to it from a battery 
of toilers which are also providing steam for a winding 
engine or other power which is very intermittent, and so 
extensive as to cause a frequent rapid reduction of pressure, 
which with some governing arrangements is quite sufficient 
to cause a disagreeable and wasteful hunting action, and 
what is still more annoying, the compressor will likely stop 
altogether if the air demand is small at the time of a sudden 
drop of boiler pressure. Of course, this stopping does not 
matter where the engine is of the wasteful cross compound 
or duplex type taking steam practically full stroke on both 
sides, as it will probably start away again as soon as more 
air is required. Where the engines are fitted with cut-off 
valves on both sides, the compressor will not start again 
when more air is required without first putting into or out 
of action some valve or other by hand, or barring the engine 
round by hand. It is then that stopping is a great nuisance. 

" There is another point in considering the governing of 
compressors fitted with Corliss or drop valves which 
frequently has been the cause of considerable hunting in 
S p ee( i — that is, the difference in the point of cut-off when 
running at a high speed and when running very slowly. The 
higher the maximum piston speed of the engine, the more 
pronounced will be this difference. 

''Considering a compressor which varies in speed according 
to the amount of air required, and where the point of cut-off 
is controlled by the air pressure, it may be at any time from 
minimum to maximum capacity. The mean pressure is 
practically constant whether running 20 or 70. The only 
difference in the steam pressure would be due to the higher 
8gm 



98 GOVERNORS AND GOVERNING MECHANISM. 

velocity of steam and air through ports, which is trifling. 
In a trip gear engine, the point of cut- off is, however, not 
constant, as the closing of the steam valves after they are 
tripped takes time. This being the case, the point of cut-off 
must be later when running at a slow speed than when 
running at a high speed, in order to produce the same mean 
pressure. This action tends to make the engines hunt when 
controlled by certain designs of governors. Suppose a com- 
pressor fitted with one of these governors is running at 20, 
and the tripping point in the steam cylinder is at 25 per 
cent of the stroke, the actual cut-off point would be almost 
directly after, say 26 per cent. In other words, there would 
be a sharp corner in the diagram owing to the compressor 
running slowly. Now, suppose a much greater volume of 
air is required, the pressure will begin to drop in the air 
receiver. This produces a later cut-off, say 27 per cent. 
The compressor at once increases in speed and is still further 
accelerated in its speed ; secondly, by the drop of pressure 
in the air receiver ; thirdly, by a considerably increased cut- 
off due to the piston speed being greater, whereas the steam 
valves take just as long to close as when running slowly 
and so adding 2 or 3 per cent to the 27 per cent cut-off. 
The result is the combined forces drive the engine to a 
higher speed than necessary and so introduces a hunting 
action. 

"Now, regarding the air pressure, the engine must not be 
allowed to run away if the air mains are opened up as to 
reduce the air pressure to only a few pounds, the pressure 
should not be allowed to vary more than 2 or 3 lbs. per 
square inch at no matter what demand, provided it is within 
the limit of the compressors. The governor should be such 
as to control the engine at the slowest possible speed, at 
which time the air that is delivered will escape through 
receiver relief valves (which would be set a few pounds 
above ordinary pressure) when there is no demand for air, 
and this irrespective of any sudden drop in boiler pressure. 
The efficient governing of a compressor presents a point of 
great economy in a high-speed compressor. It is here that 
one of the advantages of a high-speed compressor, such as 
the Riedler, is apparent. A Riedler compressor may be run 



APPENDIX. 99 

at 100 revolutions per minute, compress a certain amount 
of air, and run at a speed as low as 8 revolutions per minute 
to compress a minimum amount of air. Now compare this 
with a compressor, the maximum speed of which is only 40 
revolutions per minute and cannot be run slower than 8 
revolutions per minute without stopping. When no air is 
required, which happens frequently during the day, the 
Riedler will only be blowing away 8 per cent of its maximum 
capacity, whereas the other compressor will be blowing away 
20 per cent of its maximum capacity. Many compressors at 
mines, collieries and elsewhere, can be seen running daily at 
the maximum speed that can be got out of them, or at least 
a proportionately high speed, and probably only one-half of 
the air is used, the other half is blowing into the atmosphere, 
consequently half the coal, men's time and boiler wear, tear 
and capacity, is being wasted also. 

" To reduce this excessive waste, a number of air receivers 
are often installed, representing a great volume of stored 
compressed air, which will certainly provide for any slight 
fluctuation in the air demand, but it is surely an expensive 
means of partly overcoming the difficulty of wasted com- 
pressed air when efficient governing and one comparatively 
small receiver will entirely overcome the trouble. In fact, 
the air mains down the shaft have been found to be ample 
receiver space to enable the compressor, properly controlled, 
to do this work without waste of air without the aid of any 
receiver on the surface at all." 

Construction. — Seeing the importance of compressor 
governing, and the great saving in fuel, etc., that is effected 
thereby, Messrs. Fraser and Chalmers have now introduced 
a combined air and speed governor which fulfils all the 
conditions required. 

"This governor is shown in fig. 64 as usually arranged, and 
figs. 1, 2, and 3, diagram 1, show section through same. 
The apparatus consists of two main portions, a centrifugal 
speed governor A and a compressor governor B. This latter 
consists of a cylinder D, having a plunger C connected to a 
spring V secured to the bottom of the cylinder, where screw 
for slight adjustment is arranged. The upper part of the 
plunger is connected by necessary levers and links to one 

Lei V. * 



100 GOVERNORS AND GOVERNING MECHANISM. 




Fig. 64, 




=z . . , 



APPENDIX. 101 

end of floating lever E. This floating lever is pivoted on 
the bridle lever F, which is in connection with fly-ball 
governor sleeve. The outer end of this floating lever E 
being adapted to be attached direct or by suitable connec- 
tions to the cut-off or switch mechanism, so that any 
movement of this end will regulate the speed of the engine 
or motor. 

" In addition to the plunger C there is an internal weight S 
connected by certain levers to the plunger C, so arranged 
that the travel of the weight is greatly multiplied over the 
travel of the plunger. The flow of oil from one end of the 
weight to the other is regulated from outside the cylinder 
by an adjusting screw T (fig. 3, diagram 1), so that the 
speed or movement of the pressure plunger C can be 
controlled as desired. 

"As the weight has a considerable movement, the passage 
through the bye-pass at screw T is not so small as to become 
clogged. 

" The speed governor A consists of a governor head P 
carrying the fly-balls. These are connected by links (the 
special angle of which levers and links play an important 
part in this governor) to a spring box L, which is con- 
nected by a loose collar to the bridle lever F. 

"In this spring box is contained a short spring K, and in 
addition to this there is an independent sleeve M bearing 
upon a shoulder on the governor spindle N and between 
which and the governor head P there is a long spring 
fitted. 

"The usual design of speed and air governor consists of a 
speed governor of fly-ball type which is loaded either with 
a spring or centre weight, which spring or weight comes 
into action only when the compressor exceeds a certain 
speed near to the maximum speed of the engine, say three 
revolutions under the maximum speed. This governor so 
has nothing to do with the controlling of the compressor 
at any speed under the same. Since the compressor is 
working practically all the time under the maximum speed, 
the speed governor has therefore nothing to do with the 
controlling of the engine excepting in case of accident or 
any case where maximum revolutions is obtained. The air 



102 GOVERNORS AND GOVERNING MECHANISM. 

governor has therefore all the controlling to do ; this con- 
sists of a spring-loaded plunger, the air acting upon the 
under side of same, forcing out the plunger, which action 
would reduce the cut-off according to the amount forced out. 

" If the quantity of air to be supplied were constant, and 
the steam pressure constant, this arrangement would answer 
very well, but in no case can either constant steam pressure 
or constant quantity of air be relied on, and for this reason 
this style of governor cannot be called satisfactory. 

" As already described, the fly-ball governor is fitted with 
two springs, K ; these springs come into action at difTei'ent 
periods. Considering first spring R, it is of such a free 
length that when the governor sleeve L is about -§ in. 
from its lowest position it is just holding the spring against 
its upper bearing — that is, the sleeve L can be lifted § in. 
without compressing any spring; a small weight, or even the 
governor levers themselves, being sufficient to bring the 
governor to its lowest position when standing or running 
very slowly. 

"The spring K is of such a strength that the governor will 
gradually rise as the speed increases until it becomes close 
coiled or its upper and lower bearings are by other means 
brought into contact with each other, at which time the 
compressor will be running at its so-called maximum speed, 
the sleeve L will be, say, 2f in. above its lowest position — 
i.e., for every different engine speed there is a corresponding 
position of governor sleeve. 

" This is one of the important features of the governor — 
the entire absence of engine hunting being due to this 
feature, as it will be seen by reasoning out the action of 
the combined governor that the above-mentioned accelerating 
and retarding engine forces which create a hunting effect 
are quickly curtailed. Suppose the compressor running at, 
say, half speed, the air plunger C would be about half of its 
total travel up or outwards, the fly-ball governor sleeve 
about If in. above lowest position. The air will be at normal 
pressure. Now suppose there is a greater demand for air, 
the air pressure will begin to drop and very soon the 
plunger C will be drawn inwards. (It may be mentioned 
here that the plunger is usually made to travel its full 



APPENDIX. 103 

distance with a total rise or fall of pressure of 5 lb. per 
square iueh, or about 7 per cent of the required air pressure.) 
With the altered position of plunger C there is an extended 
cut-off given to the steam cylinder gear. Now, if the fly-ball 
governor could not change its position, hunting would 
probably commence, due to this and the other force men- 
tioned, but in this case the fact of the engine increasing in 
speed is the means of again shortening the cut-off and so 
preventing hunting, 

" The f in. free movement of governor sleeve L without 
spring pressure is introduced to prevent engine stoppiug 
altogether, the weight controlling this part being so 
adjusted as to pull down the governor to its lowest position 
when running at its minimum speed, and so considerably 
increasing the cut-off for one stroke when just on the verge 
of stopping. The upper spring only comes into action 
when the compressor exceeds its maximum speed by, say, 
5 per cent, then, as this is a very long spring and loaded to 
a safe limit, it will yield quickly, i.e., it will allow the sleeve 
L to rise another inch by the increase of speed of about five 
revolutions per minute. This spring comes into action when 
the demand for air exceeds the maximum limit of the 
engine. In fact, the various levers are so proportioned that 
the cut-off can be so shortened as to prevent the engine 
exceeding 5 per cent above its maximum speed when the air 
cylinders are doing no work at all. 

"As an explanation, suppose the gear that drives the speed 
governor were to fail, the lever F would drop to its lowest 
position and remain there. The gas or air pressure rising, 
due to the increased speed of the machine, would force the 
plunger up and with it the inner arm of the floating lever, 
thus reducing the supply of steam and preventing the 
machine from running away. Or again, suppose a greater 
amount of air is being drawn off than the compressor is 
capable of supplying, causing the gas or air pressure to drop, 
the plunger would then drop to its lowest position and 
remain stationary, the speed of the machine would then be 
controlled entirely by the speed governor. 

"The advantage gained by having the arrangement of two 
separate springs as described above can probably be best 



104 GOVERNORS AND GOVERNING MECHANISM. 

understood from an actual example. Take the case of an 
air compressor working as described above, i.e., its maximum 
working speed of 75 revolutions per minute. The speed 
governor will then be set so that at this speed the internal 
shoulder on the lower spring box L shall be just touching 
the collar on the spring sleeve M so that for any speed less 
than 75 revolutions per minute the balls will be acting 
against the lower spring only. Now, supposing a greater 
amount of air is being drawn off than the compressor is 
capable of supplying, causing the gas or air pressure to drop, 
the compressor would want to race away, but by the time 
the speed had increased to about 80 revolutions per minute 
the governor would have risen to its highest position against 
the resistance of the upper spring 0, thus shutting off the 
supply of steam and maintaining a safe speed. 

" Advantages. — In short, the result of this special design of 
speed governor is that a steady speed is maintained accord- 
ing to any amount of air required between minimum and 
maximum. In other words, the speed varies exactly as the 
volume of air required varies. The difficulty of hunting that 
has been apparent in other designs of combined speed and 
air governors is entirely overcome, and it is not dependent 
on its driving gear nor the pressure being maintained for the 
safety of the compressor. 

" Applied to Pumps. — Precisely the same governor is 
employed for pumping engines, the pressure governor 
being connected to an air vessel in the rising main, and is 
specially suitable for pumping engines that are pumping 
against a constant head and which require to run according 
to the amount of water that is drawn away. For instance, 
in waterworks' stations where the quantity of water varies 
from maximum to minimum during: the day, and where a 
certain pressure should be maintained all the time, the 
governor acts to perfection when controlling such a pumping 
engine. 

" Applied to Constant Load but Varying Speed Engines. — 
Where a pumping engine or compressor, or any engine that 
is working under a constant load, but where it may be 
required to vary the speed from time to time, tie Whitmore 
governor is a very suitable arrangement. In this instance 



APPENDIX. 105 

the pressure, or plunger part of the governor is not required. 
The cut-off switch or throttle of the engine or motor is 
connected direct to the outer end of the bridle lever F, and a 
hand wheel adjustment is provided in the rod for lengthen- 
ing or shortening the rod which connects to the bridle lever. 
By this means the engine may be run at any speed that is 
desired between minimum and maximum by the adjustment 
of this hand wheel, and should the load be suddenly released 
from the engine, no matter at what speed the engine is 
adjusted for, the engine will not exceed its maximum speed. 
Special arrangement is made in this case so that should the 
governor belts break, the stopping of the governor would 
shut off steam entirely, so that this governor has the 
advantage of absolute safety when employed in circumstances 
of this kind, as well as in the case of pumping engine and 
air compressors as before-mentioned." 

XL Tangye's Shaft Governor. — Fig. 65 shows . Messrs. 
Tangye's improved shaft governor. The following is a list 
of parts : — A, fly wheel ; B, inertia arm, carrying eccentric ; 
C, eccentric; D, centrifugal weight box; E, tension spring; 
F, tension screw ; G, tension spring box spanner ; H, inertia 
arm pivot ; I, centrifugal weight box pivot ; J, spring 
shackle and pin; K, connecting link; L, eccentric strap; 
M, eccentric rod and joint; N IS, stops; 0, lock nuts. 

This governor consists of one centrifugal weight D, one 
spring E, and the inertia arm B, carrying eccentric C, which 
is directly connected by rod and joint M to an equilibrium 
piston valve. 

The centrifugal weight is pivoted at I, and is connected 
to the inertia arm by link K, 

The inertia arm carrying eccentric is pivoted at H, and 
when the speed is suddenly increased it swings the eccentric 
across the shaft from position of maximum to that of 
minimum travel, at which the cut-off is nil ; the centrifugal 
weight also at the same time flying out and maintaining 
eccentric in position required for the altered load. 

This governor is very simple and efficient, and is used by 
Messrs. Tangye for controlling the speed of both steam and 
gas engines. 



106 



GOVERNORS AND GOVERNING MECHANISM. 



governor 



XII. Robinson 1 s Patent Shaft Governor. — This 
is shown in fig. 66. Its special features are :— 

1. The eccentric is supported and guided by an arrange- 
ment of jointless spring connections. 




Fig. 65. 



2. The governor has no spiral spring or springs, but the 
centrifugal force is balanced by the resistance to bending of 




ARTHURS F ROBINSON, ajlixa. 

„.„...,,. BECCLlfS. 




I / 
h 




, 




^p^mii?^-, ;."<_ 


:; ^-HP ? 


ll ®J:Jiv T- * ' t- ^ \- ar. ':' 


: -. » ,,.„..„ ^.^, 



TVV^ /f OB/A/SON PATENT GOVERNOR 

AS ARRANCED FOR COM TROLL INC -T HR OTTL 
ANO. AUTOMAT/C . C UT - OrrCeA R S . 



APPENDIX. 



107 



flat laminated steel blades so arranged as to form a spring, 
the strength of which can be adjusted whilst the engine is 
in motion and the speed of the engine varied as desired. 

3. All the parts are in tension, and the lever arms, which 
constitute the " balls " of this governor, balance one another 
and are arranged in such a way as to be free from inertia 
forces due to change of speed. 

Fig. 67 shows this governor arranged to operate a throttle 
valve,' the motion for the throttle valve being taken off the 
sliding sleeve. 

XIII. Butler's Fly Wheel Governor for Gas and Oil 
Engines, manufactured by Messrs. Clark Chapman and Co. 

Fig. 68 shows this governor, which operates a throttle 
valve 5 on the "mixture" supply, and is described as 

follows : — ^ 2 

"The governor consists of two wings, G 1 , G, pivoted on 
the arms°of the fly wheel W. Centrifugal force is resisted 
by the helical springs S 1 , S 2 , the ends of which rest against 
stops P, P. Each wing has a portion of a thread T, which 
actuates the sleeve E through the rollers K\ R 2 . The sleeve 
is prevented from rotating by the rollers R 3 , R 4 , running 
on the guide rails L. The endways movement of the 
sleeve is communicated to the governor shaft A by the 
fork F. The two wings are held in unison by the links 
D 1 D 2 . This governor is very powerful, and being actuated 
by inertia as well as centrifugally, the pulsating action 
of the engine shaft is sufficient to move it with the least 
change in the engine speed." 

For the 100 I.H.P. 3-cylinder compound gas engine made 
by this firm, which governs within 5 per cent from full 
load to no load, and does not hunt, the governor is 
mounted on a separate disc independent of the fly-wheel. 

Fig. 69 shows the throttle regulator used in connection 
with the above governor on Messrs. Clark Chapman's gas 
and oil engines, which have always been governed by 
"change of volume," and consequently by varying the 
compression— the system believed by the makers to be 
generally recognised as the most suitable for large power 
engines and even for car motors. 



108 GOVERNORS AND GOVERNING MECHANISM. 




APPENDIX. 



109 





110 GOVERNORS AND GOVERNING MECHANISM. 

XIV. Crossleys 1 Automatic Cut-off Gear for Gas Engines. — 
In his paper on " Recent Progress in Large Gas Engines," 
read before the British Association at Belfast, September 
11th, 1902, Mr. Humphreys speaks of this gear as follows : — 

" The great regularity of speed demanded from the modern 
gas engine has led to improved methods of governing. 
Formerly the governor controlled the ' hit-and-miss ' 
mechanism, and this is still the simplest arrangement where 
some irregularity of speed is of no consequence. Westing- 
house introduced the system of controlling the quantity of 
mixture by throttling, and this gave excellent results, but 
led to bottom loops being formed on the indicator diagram 
and wasted power. Mr. C. E. Sargeant, of America, invented 
a means of cutting off the supply of mixture at varying 
points of the suction stroke, which gave the desired result 
without wasting power. This system is the correct one, 
and is being adopted by the leading makers one after 
another, each having his special design of mechanism. 
Fig. 70 shows the cut-off gear patented by Crossley 
Brothers. The richness of the mixture remains the same, 
while the quantity admitted to the cylinder is automatically 
varied by the governor for each impulse of the engine 
according to the power required at the moment. The cut- 
off valve is placed between the admission valve and the air 
suction and gas valve. It is a cylindrical valve, with 
circumferential ports sliding axially inside the casing of the 
admission valve, which is also fitted with corresponding 
circumferential ports. The cut-off valve is in equilibrium, 
and is opened by an ordinary eccentric and rod on a side 
shaft, which works a rocking lever oscillating on a pivot, the 
position of which pivot is determined by the governor from 
time to time; the action of the governor being to turn a 
screw with right and left-hand threads on its ends, and so 
to draw the pivot towards or from the motor cylinder, 
according to the speed of the engine. Fig. 71 shows a 
series of diagrams taken from an engine fitted with the 
cut-off valve, and the wide range of power obtainable 
without missing an explosion will easily be seen." 

XV. Dunlofis Patent Combined Steam and Pneumatic 
Marine Engine Governor, manufactured by David J. Dunlop 



Track Rccb 
fhonv Governor » 




rfth 



APPENDIX. 



Ill 



and Co., Port Glasgow. Figs. 72, 73, and 74 show this 
governor. 

" For regulating and controlling the speed of machinery 
of steam ships in heavy weather," say the makers of this 
governor, " it is necessary that an attendant be in charge of 
the steam admission valve to operate it in accordance with 
the varying immersion of the vessel's stern, and so prevent 



INDICATOR DIAGRAMS FROM A CROSSLEV GAS ENGINE 
WORKING WITH PATENT CUT-OFF GEAR. 



Supply of Gas varied to suit Power Required. 




Fig. 71. 



4 racing' of the engines, with its consequent liability of 
breakdown, increased wear and tear of moving parts, and 
excessive waste of steam. 

"If an automatic mechanical apparatus be available, 
which will not only take the place of the attendant (leaving 
him free for other duties), but at the same time be certain 
and regular in action, its advantages cannot be overrated, 
as the benefits derived from it, if only through the saving of 
steam, far outweigh the first cost. 

" To properly control the speed of the engines, it is 
necessary that the steam valve shall be opened and closed 
slightly in advance of, and in exact accordance with, the 



112 GOVERNORS AND GOVERNING MECHANISM. 

varying immersed surface of the propeller, and it is only 
possible to do this when the power to work the steam valve 
is obtained directly from the varying immersion of the 
propeller or head of water at the stern of the ship. This is 
done in Dunlop's governor. 

"This governor consists of a sea-cock at the stern of the 
ship, opening into an air vessel or air chamber, so con- 
structed that, by opening the sea-cock, water is allowed to 
flow into the air vessel, and compress the air contained 
therein to a pressure equivalent to the head of water outside 
the ship. 

"From the top of the air chamber a pipe is led to the 
under side of an airtight elastic diaphragm, forming part of 
an apparatus in the engine room. On the top or upper side 
of the diaphragm there is a spiral spring, with means of 
adjusting its compression to balance the air pressure below 
the diaphragm. From the centre of the diaphragm a 
connection is made to the slide valve of a small steam 
cylinder, so constructed that its steam piston, which is 
connected by suitable gear to the steam valve of the engines 
whose speed is to be controlled, moves in exact accordance 
with the movements of the diaphragm. 

"The sea-cock being open, any variation of head of water 
outside the ship is accompanied by an inflow or outflow of 
water through it, and consequently a variation in the 
pressure of the air contained in the air vessel and under the 
diaphragm of the engine-room apparatus, causing the 
diaphragm to move through such a part of its travel as is 
requisite to enable the compression of spring and air pressure 
to balance one another again. Every movement of the 
diaphragm is followed by a corresponding movement of the 
governor steam piston, and consequently of the steam valve 
of the engines under control. The time required between 
the variation in the head of water at the stern of the ship 
and the moving of the steam valve being, so far as can be 
judged from careful experiments, absolutely nil. 

" The most important feature of Dunlop's governor is the 
fact that it will anticipate any increase in the speed of the 
engines due to the propeller rising out of the water — a 
feature which can be claimed for no other governor, as they 



; r :i 




aspinall's patent marine engine governor. 113 

one and all depend upon a variation in the speed of the 
engines to be controlled before the power to act is available. 
This anticipating action of the governor is obtained by 
adjusting the balance between the spring and the air 
pressure under the diaphragm, so that the diaphragm begins 
to fall and the steam valve to close when the tips of the 
propeller blades are anything from one to several feet under 
the surface of the water. 

"With the multiple cylinder expansion engines now 
general, unless a governor has this anticipating power it is 
practically of no use, the quantity of steam contained in the 
casings and pipes being sufficient of itself, when expanding* 
into the condenser, to cause the most serious ' racing.' " 

XYI. AspinalVs Patent Marine Engine Governor, manu- 
factured by Aspinall's Patent Governor Company, Liverpool. 
The principle on which this governor acts is the same as 
that of the gas engine inertia governor. 

The governor consists of a loose weight carried in a frame 
which is bolted to the air pump lever or to a special 
reciprocating lever fitted to the engine for the purpose. A 
lever, connecting to the main steam or throttle valve, is 
carried on a pin concentric w T ith the shaft on which the air 
pump lever w r orks, in a separate bracket close in front of the 
air pump lever carrying the governor. To prevent the 
loose weight being left behind the air pump lever as it 
descends when working at its normal speed, it is held in 
place by a small spring buffer, but should the speed of the 
engine suddenly increase through the propeller being lifted 
too far out of the water, the inertia of this weight causes 
it to overcome the resistance of the buffer and so lag behind, 
at the same time operating a pawl, which shoots out and 
engages with the under side of the throttle valve lever 
before mentioned, and this, on the next up stroke of the air 
pump lever, is carried up with it and shuts off the steam 
supply. 

The weight, on resuming its normal position due to the 
slowing down of the engine, shoots out a pawl, which 
engages with the top side of the throttle valve lever, also, 
at the same time, withdrawing the one on the lower side, 
and thus brings the lever back and again opens the 
throttle valve. 
9gm 



114 



GOVERNORS AND GOVERNING MECHANISM. 



The spring buffer, which prevents the weight being left 
behind when the engine is running at its normal speed, can 
be adjusted as required. 

In addition to the above, this governor is fitted with an 
" emergency gear," which consists of an extra small weight, 
which on coming into action, when an excessive race occurs, 
operates a latch which locks the pawls and weight in their 
shut off position and entirely prevents the re-opening of the 
throttle valve. 




Fig. 75. 

This governor is not only used on board ship, but has 
recently been introduced as an emergency governor into 
several central power stations to prevent accidents from 
racing when the governor proper has been put out of action 
through the failure of some part of the mechanism between 
engine and governor. 

Fig. 75 is an external view of this governor. 

Fig. 76 shows the governor in position on pump end of 
lever. 




Throttle YoJ/e handle 



ASPINALLS PATENT MARINE ENGINE GOVERNOR. 115 

Fig. 77 shows the general arrangement of governor on 
the engine. 

The following is a description by the makers of this 
governor : — 

" The governor consists of a hinged weight W, operating 
two pawls, P P, carried on a frame which is bolted to air 




W^Lo'^e Wtiq.hr jj A_Sma7l Weight (errfj-qr.ncttf 

P_Povr/s jj 8. Spring duffer. 

D-Detenf J /?_ Requ/o'mg Screrr.. 

&- Engayi'tq Lerer \ 



Fig. 76. 



pnmp lever or other reciprocating part. When the revolu- 
tions of engines are increased by about 5 per cent above the 
normal speed the weight W is left behind, and reverses the 
position of the pawls, causing bottom one to engage with 
lever H (fig. 76), lifting it throughout the whole upward 
stroke, and thus shutting off steam by closing throttle valve. 
On the return stroke the detent D is lifted, liberating 



116 GOVERNORS AND GOVERNING MECHANISM. 

weight W, and, if the revolutions have moderated, the 
position of the two pawls is again altered, the top pawl now 
engaging with lever H, depressing it, and thus re-opening 
the throttle valve. The emergency gear only c?mes into 
operation in case of a very excessive race, such as losing a 
propeller or a broken shaft, in which case the small weight A 
is left behind and locks the weight W in the ' shut-off' 
position, thus effectually preventing the re-opening of 
throttle valve. To unlock the emergency gear press the 
large weight W upAvards from the under side, when the 
small weight A will fall out of gear." 



INDEX. 



Air and Speed Governor (Fraser and 

Chalmers'), 96. 
Allen Link Governor, Diagram, 50. 
Angles of Crank, Trip Gear, 48. 
Aspinall's Marine Governor, 114. 
Astatic Governor, 10. 
Automatic Gear (Slide Valve), 34. 
Automatic Gear (Single Ecceutric), 34. 
Automatic Gear (Link Motion), 34. 
Automatic Gear (Joy's), 34. 
Automatic Gear (Allen Link), 34. 
Automatic Gear (Hartnell's), 37. 
Automatic Gear (Compound Link), 37. 
Automatic Gear (Meyer's), 37. 
Automatic Gear (Ryder's), 37. 
Automatic Gear (Trapezium), 39. 
Automatic Gear (Slide Valve), Table of, 

44. 
Automatic Gear (Trip), 45. 
Auxiliary Governors, S, 67, 70. 



B 

Balance of Forces, 74. 

Bell Crank Lever Governor, 18. 

Butler's Shaft Governor (Gas and Oil), 107 

Butler's Throttle Regulator, 107. 

Bursting Pressure, 3. 

Butterfly Valve, 8. 



Centrifugal Force, 3. 

Centrifugal Korce, M6an, 16. 

Circular Motion, 2. 

Clark Chapman, 107 

Combination Loaded Governor, IS. 

Compensating Springs, 23. 

Compressor Governor, 96. 

Compulsory Trip Gear, 46. 

Cone (height of), 2, 5. 

Cone (Height of, Inversely Proportional 

to Power), 17. 
Corliss Gear, 46. 
Cosine Governor, 12. 



Counterpoise, 18. 

Crank Shaft Governor, 57. 

Crossley's Automatic Gear (Gas Engine), 

110. 
Cross-armed Governor, 11. 
Curves, Speed and Load, 25, 26, 55. 



Pashpot, 12. 

Dash-pot Steam for Corliss Valves, 91. 
Dead Weight Governor, "i7, 29. 
Dead Weight Governor (Inertia of), 30. 
Diagram, Governor and Slide Valve, 50. 
Diagram, Governor, Trapezium Gear, 52. 
Diagram, Governor, Hartnell Gear, 51. 
Diagram, Governor, Allen Link, 50. 
Diagram, Governor, Trip Gear, 52. 
Diagram, Loading of Governor, 54. 
Diagram, Loading Hartnell Governor, 55. 
Diagram, Speed, Gas Engine Governor, 

66. 
Difference of Centrifugal Force, 16. 
Differential, Siemens Governor, 62. 
Dodd's Wedge Motion, 57. 
Drop Valve Gear (Single Eccentric), 46. 
Duniop Marine Engine Governor, 110. 



Economist, Mechanical, 8. 

Economist, Political, 8. 

Emergen cv Governor (Aspinall's), 114, 

116. 
Energy, Centrifugal, 3. 
Energy (total stored), 72. 
Eogine, Automatic, 24. 
Engine, Throttle Valve, 24. 
Equal Loads, 50. 
Equilibrium, 17. 
Extension of Spring, 23. 
External Forces, 13. 



Fluctuations Due to Change of Load, S. 
Fluctuations, Momentary, 30. 



118 



INDEX. 



Fly Wheel, 29. 

Fractional Loads, 27. 

Fraser and Chalmers, 04. 

Frikart (Corliss Valve Gear), 88. 

PYikart Gear, 46. 

Frikart (Hick-Hargreaves), 94. 



G 

Galloway's Parabolic Governor and Auto 
Gear, 76. 

Gas Engine Governor, 62. 

Gas Engine Governor (Clark Chapman's), 
107. 

Gas Engine Governor (Crossley's Auto), 
110. 

Gas Engine Governor (Crossley's Centri- 
fugal;, 63. 

Gas Engine Governor (Crossley's Inertia), 
66. 

Gas Engine Governor, Diagrams of 
Speed, 66. 

Gas Engine Governor (Tangye's), 105. 

Governor Gear, 32. 

Governor (Watts), 8. 

Greenwood and Batley, 88. 



Loaded Governors, 17. 

Lift of Governors, 27, 28. 

Lightness, 31. 

Load, Equal, 50. 

Loading Governor (Diagram of), 54. 



M 

Marine Engine Governor (Dunlop's), 110. 

Marine Engine Governor (Aspinall's), 113 

Marshall's Hartnell Expansion Gear, 76. 

Marshall's Proell Two- valve Gear, 83. 

Mean Centrifugal Force, 16. 

Meyer's Gear, 37. 

Moment of Centrifugal Force, 21. 

Moment of Load, 21. 

Momentary Fluctuations of Speed, 30. 



N 



Newton, 3. 



H 

Harmonic Motion, 2. 

Hartnell Gear, 37. 

Hartnell Gear, Governor Diagram, 51. 

Hartnell Governor, Speed and Load 

Curve, 55. 
Hartnell Gear (Marshall's), 76. 
Hartnell Governor, 18. 
Hartnell Governor, Power of, Table, 45. 
Hick-Hargreaves. 91. 
Hypotenuse Governor, 12. 



I 



Inertia Governor, 58. 
Inertia Governor, Upright, 62. 
Inertia Relay Governor, 67. 
Interference (Principal of), 8. 
Intermediate Positions, 21, 24, 27. 
Intersection (Point of), 10. 
Isochronism (Possibility of), 27. 
isochronous Governor, 10. 



Jerky Running of Engine, 29. 



K 

Knowles Relay Governor, 70. 



One-speed, en y-position Governor, 10. 
One-speed, one-position Governor, 10. 



Parabolic Governor, 10. 

Parabolic Governor, 76. 

Parallelogram of Forces, 5. 

Pendulum, Conical, 2, 5. 

Pendulum, Swing of, 7. 

Pickering Governor, 18. 

Pickering Governor, Powers of, Table,. 

33. 
Pneumatic Marine Engine Governor, 110. 
Porter Governor, 17. 
Power, 14, 15. 
Power, Governor, 72. 
Power, Governor, Definition, 74. 
Power (Increase of), 17. 
Power, Inversely Proportional to Height 

of Cone, 17. 
Power, Lifting and Forcing, 72. 
Power (Relative), 16, 23. 
Pressures on Piston (Mean Effective), 50. 
Proell Apparatus (Storev's), 81. 
Proell Two-valve Gear (Marshall's), S3. 
Pumping Engine Governor, 104. 



Qualifications Governors Possess, 15 



INDEX. 



110 



R 

Range of Governor, 2S. 
Reducing Valve, 32. 
Regulating Power, S. 
Regularity, 24. 

Relative Power of Governor, 16, 
Relay Governor, Inertia, 67. 
Relay Governor, Knowles', 70. 
Resistances, External, 72. 
Resistance of Spring, 28. 
Reversing (Corliss) Trip Gear, 94. 
Revolution (Time of), 6. 
Richardson, J., 72. 

Richardson-Rowland Gear (Robey's), < 
Rite's Governor, 62. 
Robinson's Shaft Governor, 106. 
Rocking Valve, 79. 
Ryder Gear, 37, 



Self- regulation, S. 

Sensitiveness, 23. 

Sbaft Governor, 31, 57. 

Shaft Governor (Butler's Gas and Oil), 107 

Shaft Governor (Robinson's), 106. 

Shaft Governor (Tangye's), 105. 

{Siemens' Governor, 62. 

Spring & Dead Weight Loaded Governor. 

18. 
Spring (Compression), 27. 
Spring, Extension of, 23. 
Spring Loaded Governor, 18, 27. 
Static, 10. 
Steadiness, 29. 

Steadying Effect of Inertia, 30. 
Steam Chest (Size of), 33. 
Storey s Proell Apparatus, 81. 



Supplementary Governor, Knowles', 70. 
Supply and Demand, 1, 8. 
Suspension (Point of), 12. 



Table, Hartnell Governors, 45. 

Table, Pickering Governors, 33. 

Table, Slide Valve Gears, 44. 

Tan gye- Johnson Automatic Gear, 77. 

Tangye's Shaft Governor, 105. 

Throttle Regulator (Clark Chapman's 



Gas Engine), 107. 
Throttle Valve Gear, 
Trapezium Gear, 37. 
Trip Gear, 45. 



32. 



u 



V 



Unsteadiness, 29. 



Variation, 23. 
Valve Gear, 28. 



w 

Watt, James, ]. 

Watt Governor, 8. 

Whitmore Controller, 95. 

Willans' Governor, 23. 

Winding Engine (Corliss), 96. 

Work, Compressing Spring, 73. 

Work, External, 73. 

Work, Total done by Governor, 73. 



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